NANCY Pelosi has warned Boris Johnson there is “no chance” of a US-UK trade deal passing through Congress if Brexit puts Northern Ireland’s Good Friday Agreement at risk.

Pelosi, the Speaker of the United States’ House of Representatives, made the comments after John Bolton, the US national security adviser, said the UK would be “front of the queue” for new trade deals when he visited London earlier this week.

His remarks were welcomed by Brexiteers. “No longer at the back of the queue,” Leader of the House of Commons Jacob Rees-Mogg tweeted, with a link to Bolton’s comments.

But responding to Bolton, Pelosi said: “The Good Friday Agreement serves as the bedrock of peace in Northern Ireland and as a beacon of hope for the entire world. After centuries of conflict and bloodshed, the world has witnessed a miracle of reconciliation and progress made possible because of this transformative accord.

“Whatever form it takes, Brexit cannot be allowed to imperil the Good Friday Agreement, including the seamless border between the Irish Republic and Northern Ireland, especially now, as the first generation born into the hope of Good Friday 21 years ago comes into adulthood. We cannot go back.

“If Brexit undermines the Good Friday accord, there will be no chance of a US-UK trade agreement passing the Congress. The peace of the Good Friday Agreement is treasured by the American people and will be fiercely defended on a bicameral and bipartisan basis in the United States Congress.”

Johnson has demanded the EU scrap the backstop plan to keep the Irish border open if no trade deal is agreed in the transition period after a Brexit based on the Withdrawal Agreement, but Brussels has refused to budge, increasing the possibility of a No Deal and border checks.

The UK currently trades with the US under the EU’s trade rules, which must be followed by all member states. One of the main arguments in favour of a hard Brexit used by Brexiteers is that the arrangement would leave the UK free to negotiate new trade deals with other countries.

But if the UK’s post-Brexit rules diverge greatly from the EU’s, it compounds the problems on the island of Ireland – the more different the rules are, the more necessary a hard border between Northern Ireland and Ireland would be. Pelosi first warned about the prospect of a future UK/US trade deal should the peace process be undermined when she visited Ireland in April.