BAGHDAD -- The Iraqi government began a long-awaited, large-scale military operation on Monday to dislodge Islamic State militants from the country's sprawling western Anbar province, a military spokesman announced.

The spokesman for the Joint Operations Command, Brig. Gen. Yahya Rasool, said in a televised statement that the operation started at dawn and that government forces were being backed by Shiite and Sunni pro-government fighters. Rasool did not say whether the U.S.-led international coalition was taking part.

This is not the first time the Iraqi government has announced an operation to retake Anbar -- where several key towns, including the provincial capital, Ramadi, remain under Islamic State control. In May, authorities announced an operation to retake Ramadi, but there has not been any major progress on the ground since then.

In a brief statement, Iraqi Prime Minister Haider al-Abadi vowed to "take revenge from Daesh criminals on the battlefield ... and their cowardly crimes against unarmed civilians will only increase our determination to chase them and to expel them from the land of Iraq."

The Islamic State group, also known by the Arabic acronym Daesh, seized large parts of Anbar in early 2014 and captured Ramadi in May. Iraqi forces, which had been making steady progress against the extremists in recent months with the help of the air campaign, scored a major victory in recapturing Saddam Hussein's hometown of Tikrit in April.

During the past few weeks, the troops have been moving to cut the militants' supply routes and to surround and isolate Ramadi and Fallujah.

Rasool didn't provide any further details on the ongoing operations. By noon, the country's state TV reported government forces recapturing villages and areas around Fallujah, which is located half way between Baghdad and Ramadi.

Hours after the announcement of the military operation, Iraq's Defence Ministry announced the arrival of four F-16 fighter jets from the United States to Balad air base north of Baghdad. They are part of 36 F-16s purchased by the Iraqi government.

The new fighter jets will boost Iraq's air force, which depends only on several Russian-made secondhand Sukhoi jets. Last week, a Sukhoi fighter jet accidentally dropped a bomb over a Baghdad neighbourhood, killing at least 12 people.

Meanwhile, U.S.-led coalition forces continued their aerial campaign across Iraq and Syria, ramping up attacks near Ramadi, which IS captured in May. A statement by the Combined Joint Task Force - Operation Inherent Resolve said that 29 airstrikes struck 67 IS staging areas near Ramadi over the previous day. The strikes destroyed two IS excavators, a militant armoured personnel carrier, and a militant vehicle, the coalition said.

Also, on Monday, the Islamic State group claimed responsibility for a series of bombings Sunday in Shiite areas of Baghdad that killed at least 29 people and wounded 81.

Iraq is going through its worst crisis since the 2011 withdrawal of U.S. troops. The Islamic State group controls large swaths of the country's north and west after capturing Iraq's second-largest city of Mosul and most of Anbar.

In neighbouring Syria, government helicopter gunships dropped barrel bombs on a diesel market in the northern town of al-Bab that is held by the Islamic State group, activists and pro-IS social media pages said.

The Britain-based Syrian Observatory for Human Rights said Monday's airstrikes killed 13 people, including six women, and wounded as many as 40. A Facebook page used by Islamic State supporters said 35 people died. The discrepancy could not be immediately resolved.

Monday's attack on al-Bab came two days after activists said army airstrikes killed at least 28 people in the town, which is a frequent target of Syrian army strikes that often kill civilians. On May 31, Syrian army airstrikes that hit a packed market in al-Bab killed around 70 people, most of them civilians.