Zelensky met with Austin on the sidelines of the Shangri-La Dialogue, a major security forum attended by defence officials from around the world.

The meeting came after Washington decided to partially lift restrictions on using US-provided weapons to strike inside Russia, which Zelensky has hailed as a "step forward".

Asked about the meeting by reporters as he left the room, the Ukrainian president said it was "very good". Austin made no comment.

A US official travelling with Austin had told AFP the pair would meet to "discuss the current battlefield situation in Ukraine and to underscore US commitment to ensuring Ukraine has what it needs to defend itself against ongoing Russian aggression".

Zelensky is appealing for more military aid for the Ukrainian army, which has been ceding ground to relentless Russian attacks.

Zelensky and Austin last met face-to-face in December in Washington, where Zelensky made a last-ditch plea for US aid before it ran out.

The US Congress approved in April a $61 billion financial aid package for Ukraine following months of political wrangling, unlocking much-needed arms for the country's outgunned troops.