KYIV/WASHINGTON: Ukrainian President Volodymyr Zelenskiy is expected to travel to Washington, meet President Joe Biden and visit Congress on Wednesday, sources familiar with the matter said, in his first known overseas trip since Russia's invasion on Feb. 24.

The United States is expected to announce a package of military assistance for Ukraine, valued at about $1.8 billion, U.S. officials said separately, on condition of anonymity.

The package would include aid and Patriot missiles but its value could still change, the officials added. One of the officials said the package could include guidance kits for air-launched missiles to help Ukraine strike targets with precision.

Zelenskiy and Biden are expected to meet at the White House, one of the sources said.

CNN reported that Zelenskiy was already on his way to Washington.

Zelenskiy's spokesman did not respond to a request for comment. The president last left Ukraine for a Munich Security Conference on Feb. 19, according to his official schedule.

His trip abroad 10 months into the war was expected to include a visit to lawmakers at the U.S. Capitol, a source familiar with the planning said on Tuesday.

The trip had not been confirmed and security concerns could force a change in plans, the source said.

U.S. House of Representatives Speaker Nancy Pelosi's office did not immediately respond to a request for comment.

Earlier on Tuesday, Pelosi said in a letter that there would be a session of Congress on Wednesday night which would have a "very special focus on democracy".

'FORTRESS BAKHMUT'

Zelenskiy had earlier made a surprise trip to the eastern frontline city of Bakhmut, his office said on Tuesday, underlining Russia's stuttering but persistent attempts to capture it.

In his nightly video address, Zelenskiy referred to the visit as a trip to "Fortress Bakhmut" in Donetsk, a province Russia claimed in September. Most countries reject Russia's claim as an illegal occupation.

Dressed in combat khaki, Zelenskiy handed out medals to soldiers in a tumble-down industrial complex to applause, video released by his office showed.

In contrast, Russian President Vladimir Putin awarded medals in the comfort of the Kremlin to the Russian-appointed leaders of four regions of Ukraine that Russia has claimed to have annexed since invading its neighbour.

Video footage released on Ukrinform TV, part of Ukraine's state news agency, showed servicemen in Bakhmut handing Zelenskiy a Ukrainian flag with their signatures on it.

"We will turn it over to the Congress and to the U.S. president from the guys," Zelenskiy said in the video, without giving any further details. "We are grateful for the support. But it's not enough," he added.

He has urged the troops to keep up their spirits as the battle for Bakhmut, one that has come to symbolise the grinding brutality of the war, enters its fifth month.

"The east is holding out because Bakhmut is fighting. In fierce battles and at the cost of many lives, freedom is being defended here for all of us," Zelenskiy wrote on the Telegram messaging app.

CALL FOR AID

Zelenskiy has repeated calls to the West for more weaponry including air defence systems after Russian drones hit energy targets in a third strike on power facilities in six days.

Washington is close to finalising plans to send the Patriot missile defence system to Ukraine, according to sources, but the Kremlin has warned the U.S.-supplied equipment would be a legitimate target for Russian strikes against Ukraine.

The U.S. Senate has advanced a government-funding bill that includes $44.9 billion in emergency assistance to Ukraine and NATO allies. The money would be used for military training, equipment, logistics and intelligence support, as well as for replenishing U.S. equipment sent to Ukraine.

The World Bank on Tuesday said it had approved an additional financing package for Ukraine totalling $610 million to address urgent relief and recovery needs.

Kyiv has argued it needs Western help to strengthen its air defences as Russian strikes have repeatedly cut electricity and water supplies in subzero winter temperatures.

Ukrainian officials say Russia's missiles and bombardments are aimed at breaking the will of civilians.

Prime Minister Denys Shmyhal said Ukrainians should prepare for new attacks by Russia on energy infrastructure because it wanted them to spend Christmas and the New Year in darkness.

Electricity supplier YASNO, which covers the area of the capital Kyiv, offered no immediate respite for residents.

"We are not even counting on a return to scheduled disconnections," Sergey Kovalenko, YASNO chief executive, said in a Facebook post late on Tuesday.

(Reporting by Reuters bureaus; Writing by Grant McCool and Himani Sarkar; Editing by Cynthia Osterman and Stephen Coates)