KYIV (Reuters) - Britain's opposition Labour Party affirmed its "ironclad" commitment to Ukraine during a visit to Kyiv on Monday by the party's foreign and defence chiefs.

David Lammy and John Healey met Ukraine's defence minister and President Volodmyr Zelenskiy's top aide on the visit, during which they travelled to suburbs scarred by Russia's occupation early in the war and paid their respects to victims in the towns of Bucha and Irpin.

Britain's Labour Party polls well ahead of the governing Conservatives ahead of a national election expected later this year.

"If there is a change in government at the election in Britain this year, there will be no change in Britain's resolve to stand with Ukraine, to confront Russian aggression and to pursue Putin for his war crimes," Healey told Reuters.

As the war grinds through its third year, Ukraine is on the back foot after delays in foreign military aid supplies and mounting pressure from Russia on the battlefield.

Conservative Prime Minister Rishi Sunak has announced an increase in British support for Ukraine and said he would lift overall defence spending to 2.5% of GDP a year by 2030.

Healey said the Labour Party "matches the government's ambition on raising defence spending to 2.5%" as soon as possible, and would hold a strategic defence review in the first year Labour is in power.

Before coming to Ukraine, Lammy visited Washington, a key ally of Kyiv, that holds a presidential election in November that pits incumbent Joe Biden against former president Donald Trump.

"I am really pleased that Donald Trump seemed to signal the importance of granting that $61 billion [in Ukraine aid] and what we are hearing is that the aid is now beginning to come into Ukraine," Lammy said.

Lammy and Healey discussed air defences, longer-range fires and an upcoming Kyiv-promoted peace summit when they met Ukrainian officials, they said.

President Zelenskiy said earlier that he expects between 80 and 100 countries to attend a high-level peace summit next month in Switzerland that aims to rally support for Ukraine's vision of ending the war.

"The U.K. has a key and important partnership with Commonwealth countries and the Global South," Lammy said. "We will use all of our endeavours to support Ukraine in ensuring as many countries as possible attend the peace conference."

(Reporting by Anastasiia Malenko; editing by Christina Fincher)

By Anastasiia Malenko