The US House of Representatives has approved legislation to give aid to Ukraine, with more than a dozens Republicans defying their leadership to vote in favour of the measure.

Some 18 Republicans joined the Democrats to back the Ukraine Support Act on Thursday, which passed in a 226 to 195 vote.

It's the latest instance of Republicans breaking from President Donald Trump in recent days.

However, it's unlikely the bill will become law, as it must also be passed by the Senate and then gain Trump's signature.

In a largely symbolic vote earlier this week, a handful of Republicans in the House backed a resolution seeking to stop Trump from taking further military action in Iran.

The Trump administration also dropped its plans to create an "anti-weaponisation" fund, after strong criticism from Democrats and some Republicans.