Zelensky is expected to attend an EU summit in Brussels on Thursday as part of only his second foreign trip abroad since Russia launched its invasion almost a year ago.

"My president travels to get results," a Ukrainian official, speaking under condition of anonymity, told journalists. "First and foremost, the main result is weapons."

The official said that Zelensky would urge the European Council, made up of the 27 leaders of the EU's member states, "to speed up arms deliveries to Ukraine".

European diplomats told AFP that Zelensky would hold bilateral meetings with some member EU state leaders on the sidelines of the summit since he knows that the bloc itself has no weapons to supply.

The Ukrainian official said Kyiv urgently needs ammunition, artillery, battle tanks and fighter jets to help stave off a new Russian assault and to renew its own counter-offensive.

The official said the demand for jets was "not unrealistic" and that Kyiv expected the process to move faster than it had on the delivery of tanks.

Zelensky visited London on Wednesday and won a commitment to start training Ukrainian fighter pilots on NATO standard jets. He called for Britain and "the world" to supply combat aircrafts.

The Ukrainian official also said that Zelensky would focus on pushing his country's bid to join the EU and try to secure widespread support for Kyiv's peace plan proposals.

The official reiterated the call from Zelensky at a meeting with top EU officials last week for Brussels to start formal accession negotiations with Kyiv this year.

"We would not like to be the hostages of any bureaucratic obstacles," the official said.