WARSAW, POLAND -- A top-level U.S. congressional delegation led by House Speaker Nancy Pelosi was in Warsaw on Monday to express gratitude to Poland for their humanitarian and other support for Ukraine.

Pelosi and a half dozen U.S. lawmakers met with President Andrzej Duda and Polish lawmakers in Warsaw. The visit followed a weekend visit to Kyiv where they met with Ukrainian President Volodymyr Zelenskyy, pledging to support his country until it defeats Russia.

In a statement after the meeting with Duda, Pelosi called him "a valued partner in supporting the people of Ukraine in the face of Putin's brutal and unprovoked war."

She said that during their meeting the members of her delegation "expressed America's deep gratitude to the Polish government and Polish people for opening their hearts and homes to Ukrainian refugees, and we reaffirmed our nation's pledge to continue supporting Poland's humanitarian efforts."

Russians invasion of Ukraine has sparked a refugee crisis, with more than 5.5 million people fleeing the country. The largest group by far -- more than 3 million people -- have arrived in Poland, and many of them have remained.

Regular Polish people have taken Ukrainians into their homes, while the government and volunteers have mobilized to help in countless ways.

The trip came two days after U.S. President Joe Biden asked Congress for US$33 billion to bolster Ukraine's fight against Russia, more than twice the size of the initial $13.6 billion aid measure that now is almost drained. The measure is designed to signal to Russian President Vladimir Putin that U.S. weaponry and other forms of assistance aren't going away.

During a news conference on Sunday in Rzeszow, Poland, the members of the congressional delegation were unanimous in praising Ukraine's defenses, in painting the battle of one as good against evil and in assuring continued long-term U.S. military, humanitarian and economic support.