“We believe that we are visiting you to say thank you for your fight for freedom … Our commitment is to be there for you until the fight is done,” Pelosi told Zelensky, according to a video from the Ukrainian presidency.

Zelensky tweeted: “Thank you to the US for helping protect the sovereignty and territorial integrity of our state”.

“The US is leading strong support for Ukraine in its fight against Russian aggression,” he said.

The trip by a Congressional delegation had not been previously announced.

“Our delegation proudly delivered the message that additional American support is on the way, as we work to transform President Biden’s strong funding request into a legislative package,” Pelosi’s office said in a statement.

US President Joe Biden last week proposed a huge US$33-billion package for arming and supporting Ukraine.

Biden also outlined proposed new laws to allow using luxury assets stripped from Russian oligarchs to compensate Ukraine for the destruction wreaked by the invading Russians.

“When we return to the US, we will do so further informed, deeply inspired and ready to do what is needed to help the Ukrainian people as they defend democracy for their nation and for the world,” Pelosi’s statement continued.

US Secretary of State Antony Blinken and US Defense Secretary Lloyd Austin visited Kyiv last month.