The speaker of the US house of representatives has defied Donald Trump by leading a pro-Nato delegation to Brussels and restating US commitment to the defence of Europe.

Nancy Pelosi said there was strong cross-party support in the congress for the Atlantic alliance – and that the American legislature had asserted itself over Mr Trump.

The US president has questioned his country’s commitment to Nato, arguing that Europe should fund more of its own defence and relies too much on the US for protection.

He has also sought to frustrate the speaker’s efforts to make foreign visits, cancelling a planned visit to American troops in Afghanistan.

In Brussels on Tuesday morning with a cross party delegation from the US congress to the Nato parliamentary assembly, Ms Pelosi said: “I think our message is a very clear one – when 10 per cent of the congress comes to Europe for the Munich Security Conference as well as continuing on here with even more additional members present.

“Once the Democratic-Republican colleagues had this opportunity to vote [on the Nato support act] I think that sends a very clear message.”

As well as attending the parliamentary assembly, the speaker met European Commission Jean-Claude Juncker and other officials.

In a veiled broadside at President Trump, she added: “We’re not a parliamentary government: we have Article 1, the legislative branch, the first branch of government, co-equal to other branches, and we have asserted ourselves in that way.”

Donald Trump has hardened US policy towards Europe (AP)

Asked whether there was a party divide on the issue of Nato membership in the US, Ms Pelosi said: “I don’t think there’s any difference between Democrats and Republicans on our relationship with Nato – this is not partisan in any way.”

Around 50 US senators and representatives attended the Munich Security Conference last week, with yet more joining them for the Nato parliamentary assembly in Brussels.

A spokesperson for the European Commission said: “Yesterday the meeting with president Juncker [and Nancy Pelosi] was a very cordial and wide-ranging discussion, very positive. It covered all issues that pertain to EU-US transatlantic relations but also many aspects of what we call the global agenda – where we still believe that the EU and US share a lot, have many shared and common interests to defend this global agenda. This was the discussion, and it was a good one.”

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The visit by the congressional delegation to Europe comes at a time of worsening relations between the Trump administration and the EU.