KABUL, AFGHANISTAN -- Taliban forces sealed off Kabul's airport Saturday to most Afghans hoping for evacuation, as the U.S. and its allies were ending a chaotic airlift that will end their troops' two decades in Afghanistan.

Western leaders acknowledged their withdrawal would mean leaving behind some of their citizens and many locals who helped them over the years, and they vowed to try to continue working with the Taliban to allow local allies to leave after U.S. President Joe Biden's Tuesday's deadline to withdraw from the country.

Although most of its allies had finished their evacuation flights, the U.S. planned to keep its round-the-clock flights going until the deadline, saying 113,500 people had been evacuated since Aug. 14, the day before the Taliban claimed Kabul. Biden warned Saturday that commanders had told him another attack was "highly likely in the next 24-36 hours," and the U.S. Embassy issued a new warning early Sunday for all Americans to avoid the airport area entirely.

Britain ended its evacuation flights Saturday, though Prime Minister Boris Johnson promised to "shift heaven and earth" to get more of those at risk from the Taliban to Britain by other means.

Britain's ambassador to Afghanistan, Laurie Bristow, said in a video from Kabul airport and posted on Twitter that it was "time to close this phase of the operation now."

"But we haven't forgotten the people who still need to leave," he said. "We'll continue to do everything we can to help them. Nor have we forgotten the brave, decent people of Afghanistan. They deserve to live in peace and security."

As the flow of planes leaving Kabul slowed, others arrived in locales around the world carrying Afghans who managed to secure places on the last evacuation flights, including in the Washington area, Philadelphia, Madrid, and Birmingham, England. Some passengers were relieved and looking forward to starting new lives far from the Taliban, but others were bitter about having to flee.

In Spain, Shabeer Ahmadi, a journalist targeted by the Taliban, said the United States had doomed the work he and others had put into making Afghanistan a better place by allowing the insurgent group to reclaim power.

"They abandoned the new generation of Afghanistan," Ahmadi said.

An evacuation flight to Britain landed with an extra passenger after the cabin crew delivered a baby girl midair, Turkish media reported. The parents named her Havva, or Eve, and she was at least the fourth baby known to have been born to Afghan mothers who went into labor on evacuation flights.

Meanwhile, families of Afghans killed in Thursday's suicide bombing at the airport by an Islamic State group affiliate continued burying their dead -- at least 169 Afghans and 13 U.S. service members were killed. Among them was Belal Azfali, a 36-year-old contractor for a U.S.-funded project who had gone to the airport on his own, without his wife. His remains were so disfigured that he could only be identified when someone picked up the family's repeated calls to the cellphone he had with him, relatives said.

The U.S. on Saturday released the names of the 13 Marines, Navy and Army personnel who were killed in the bombing. One of the Marines -- recently promoted Sgt. Nicole Gee, 23 -- was seen in a widely circulated photo cuddling an Afghan infant temporarily rescued from the crush of the crowds outside the airport gates this month.

Taliban spokesman Zabihullah Mujahid claimed Saturday that the group's forces were holding some positions within the airport and were ready to peacefully take control of it as American forces flew out. But Pentagon spokesman John Kirby denied the claim.

The Taliban did deploy extra forces outside of the airport to prevent large crowds from gathering in the wake of Thursday's bombing . New layers of checkpoints sprang up on roads leading to the airport, some manned by uniformed Taliban fighters with Humvees and night-vision goggles captured from Afghan security forces. Areas where the crowds had gathered over the past two weeks in the hopes of fleeing the country were largely empty.

Officials said U.S. forces were taking every precaution at the airport, as there were concerns that IS, which is far more radical than the Taliban, could strike again. A new security alert from the U.S. Embassy on Sunday morning said due to a "specific, credible threat" all U.S. citizens should avoid certain gates at the airport and avoid traveling to the area.

In his statement earlier, Biden said a drone strike he ordered that killed what military officials described as two "high-profile" IS militants believed to have been involved in planning or facilitating attacks would not be his "last" response to Thursday's suicide attack.

An Afghan who worked as a translator for the U.S. military said he was with a group of people with permission to leave who tried to reach the airport late Friday. After passing through three checkpoints they were stopped at a fourth. An argument ensued, and the Taliban said they had been told by the Americans to only let U.S. passport-holders through.

"I am so hopeless for my future," the man later told The Associated Press, speaking on condition of anonymity because of security concerns. "If the evacuation is over, what will happen to us?"

Kirby, the Pentagon spokesman, said Saturday that Afghans who had worked with American forces still were being allowed in.

According to a State Department spokesperson, 5,400 Americans and likely more have been safely evacuated from Afghanistan since Aug. 14, including nearly 300 Americans in the last day. Another 350 were still seeking to leave the country, and those were the only ones the department could confirm were still in Afghanistan.

Biden has said he will adhere to a self-imposed Tuesday deadline for withdrawing all U.S. forces, and the Taliban have rejected any extension. They have encouraged Afghans to stay, pledging amnesty even to those who fought against them, and have said commercial flights would resume after the U.S. withdrawal, but it's unclear if airlines will be willing to offer service.

As the deadline neared and with the Taliban controlling nearly all of the country, hundreds of protesters, including many civil servants, gathered outside a bank while countless more lined up at cash machines. They said they hadn't been paid for three to six months and were unable to withdraw cash. ATM machines were operating, but withdrawals were limited to about US$200 every 24 hours. Later Saturday, the central bank ordered commercial bank branches to open and allow customers to withdraw $200 per week, calling it a temporary measure.

The economic crisis, which predates the Taliban takeover, could give Western nations leverage as they urge Afghanistan's new rulers to form a moderate, inclusive government and allow people to leave after Tuesday.

Afghanistan is heavily dependent on international aid, which covered around 75% of the toppled Western-backed government's budget. The Taliban have said they want good relations with the international community and have promised a more moderate form of Islamic rule than when they last governed the country, but many Afghans are deeply skeptical.

The Taliban cannot access almost any of the central bank's $9 billion in reserves, most of which is held by the New York Federal Reserve. The International Monetary Fund has also suspended the transfer of some $450 million. Without a regular supply of U.S. dollars, the local currency is at risk of collapse, which could send the price of basic goods soaring.

The U.S. and its allies have said they will continue providing humanitarian aid through the UN and other partners, but any broader engagement -- including development assistance -- is likely to hinge on whether the Taliban deliver on their promises of more moderate rule.

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Faiez reported from Istanbul, Lawless reported from London and Knickmeyer reported from Oklahoma City. Associated Press writers Frances D'Emilio in Rome, Joseph Krauss from Jerusalem, Robert Burns in Washington, Arritz Parra in Madrid and Kathy Gannon in Islamabad contributed to this report.

Correction:

An earlier version of the story contained an incorrect figure for the evacuation total since Aug. 14.