WASHINGTON/KYIV (Reuters) -President Volodymyr Zelenskiy, on his first wartime foreign visit, told the U.S. Congress on Wednesday that aid to Ukraine is an investment in democracy and not charity, and he invoked American efforts to defeat the Nazis in World War Two.

Seeking more U.S. support for Kyiv’s war effort, Zelenskiy, wearing his trademark olive green pants and sweater, earlier met President Joe Biden at the White House.

Biden urged Americans and the world to keep backing Kyiv in 2023, when congressional approval for aid will be harder to secure.

The United States has sent about $50 billion in assistance to Kyiv as Europe’s biggest land conflict since World War Two drags on, killing tens of thousands of people, driving millions from their homes and reducing cities to ruins.

But some Republicans, who will take control of the House of Representatives from Democrats on Jan. 3, have expressed concerns about the price tag. They could hold up billions of dollars in war aid starting next month.

“Your money is not charity. It is an investment in the global security and democracy that we handle in the most responsible way,” Zelenskiy told a joint session of the U.S. Senate and House of Representatives, speaking in English.

He also said the world was too interconnected to allow any country to stand aside and feel safe.

Members of Congress stood, cheered, applauded and shook Zelenskiy’s hand as he entered the chamber, with several wearing the colours of the Ukrainian flag, blue and yellow.

Referencing former U.S. President Franklin D. Roosevelt, who served between 1933 and 1945, and efforts to liberate Europe from Nazi occupation, Zelenskiy also appealed to Americans as they gathered with family for Christmas.

“Just like the brave American soldiers, which gave their lives and fought back Hitler’s forces during the Christmas of 1944, brave Ukrainian soldiers are doing the same…this Christmas,” he said.

The Battle of the Bulge began in December 1944 was Hitler’s final major attempt to push back Allied forces. Poor weather hampered initial U.S. efforts to halt the offensive, leading to fatalities and threatening to divide allies. Allied forces ultimately prevailed.

Earlier, U.S. Secretary of State Antony Blinken announced the United States would provide another $1.85 billion in military aid for Ukraine including the highly advanced Patriot air defence system to help it ward off barrages of Russian missiles.

But some hard-line Republicans have urged an end to the aid for Ukraine, instead calling for an audit to trace how the money previously allocated has been spent.

Zelenskiy has repeatedly called on the West to supply more advanced weaponry, ranging from modern battle tanks to missile defence systems, but Western allies have been cautious, keen to minimise any risk of provoking wider conflict with Russia.

Zelenskiy earlier meet Democratic and Republican leaders in the Senate and House of Representatives.

(Reporting by Reuters bureaus; Writing by Costas Pitas; Editing by Cynthia Osterman)