KYIV, May 1 (Reuters) - U.S. House of Representatives Speaker Nancy Pelosi said on Sunday said she had met Ukrainian President Volodymyr Zelenskiy in Kyiv to send the message that the United States stands firmly with Ukraine as it battles "Putin's diabolic invasion."

Zelenskiy, flanked by an armed escort, greeted Pelosi outside his presidential office, dressed in the khaki military garb he has worn for public appearances since the start of Russia's invasion on Feb 24.

"Our delegation traveled to Kyiv to send an unmistakable and resounding message to the entire world: America stands firmly with Ukraine," Pelosi said in a statement.

She was accompanied by several lawmakers on a congressional trip that followed a visit last weekend to Ukraine by Secretary of State Antony Blinken and Secretary of Defense Lloyd Austin.

Pelosi said Zelenskiy had made clear Ukraine needed more security, economic and humanitarian aid "to address the devastating human toll taken on the Ukrainian people by (President Vladimir) Putin's diabolic invasion".

"Our delegation proudly delivered the message that additional American support is on the way," she said.

On Friday, Pelosi said she hoped to pass a $33 billion aid package for Ukraine requested by President Joe Biden as soon as possible - a dramatic escalation of U.S. funding for Ukraine more than two months after Russia launched what it calls a "special military operation."

"The United States is the leader in strong support for Ukraine in the fight against Russian aggression. Thank you for helping to protect the sovereignty and territorial integrity of our state," Zelenskiy said on Twitter, sharing a video of the meeting with Pelosi.

Biden's funding request includes over $20 billion for weapons, ammunition and other military assistance, as well as $8.5 billion in direct economic assistance to the Ukrainian government and $3 billion in humanitarian aid.

Pelosi's delegation, which included Foreign Affairs Committee Chairman Gregory Meeks, travelled onward from Ukraine to Poland for meetings with President Andrzej Duda and other senior officials, according to its statement.

As House speaker, Pelosi is the second in line to succeed Biden, after Vice President Kamala Harris.

Moscow says its actions aim to disarm Ukraine and rid it of anti-Russian nationalism fomented by the West. Ukraine and the West say Russia launched an unprovoked war of aggression.