Nancy Pelosi makes a point to Taoiseach Leo Varadkar at the Republics Department of Foreign Affairs

Sir Reg Empey was speaking after she warned there would be no post-Brexit trade deal between America and the UK if any “harm” comes to the 1998 accord.

Mrs Pelosi, a Democrat who is speaker of the US House of Representatives, spoke at the Republic’s Department of Foreign Affairs at the start of a two-day visit to Ireland.

According to the Press Association, she said of a trade deal: “That’s just not on the cards, if there’s any harm done to the Good Friday accords... don’t even think about that.”

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The BBC further quoted her as saying “it is very hard to pass a trade bill in the congress... but if there were any weakening of the Good Friday accords, there would be no chance whatsoever”.

She also said the deal “ended 700 years of conflict” and is “a model to the world”, the BBC added.

UUP peer Lord Empey – who was party’s lead negotiator on the parts of the agreement which set up Northern Ireland’s government structures – hit out at her for her “complete misunderstanding” of the 1998 deal.

He said congress had been “hypnotised” by the views espoused by the Irish government, which has been “throughout this process using the Good Friday Agrement as a tool”.

In short, Mrs Pelosi’s position seems to be the UK should do what the Republic’s government wants, or forfeit a trade deal – a position Lord Empey likened to “an attempt to blackmail people”.

He wondered where Mrs Pelosi had developed her understanding of the agreement’s content, noting that the current Dublin administration does not contain anyone who helped forge the deal, and that Sinn Fein were absent from key parts of the talks – and in any case “didn’t support the agreement at the time” anyway.

“I’d be helpful if the speaker actually spoke to some people who negotiated the agreement,” he said.

“Because some of the proposals in the Withdrawal Agreement – including the backstop – actually are an attack on [the 1998 deal]...

“I’ve never come across a time when there’s been so many experts on the Good Friday Agreement, and yet most of the people who’re spouting about it weren’t within a mile of it.”

He said party leader Robin Swann is hoping to meet her, and would be able to “correct” her take on the 1998 deal.