"Bumbling" Foreign Secretary Boris Johnson is making the UK a "laughing stock", the SNP Westminster leader has claimed.
Ian Blackford launched a scathing attack on Mr Johnson during Prime Minister's Questions, arguing that the Foreign Secretary's leaked letter on the Irish border "shows he can't get to grips with one of the most fundamental issues of Brexit".
The Ross, Skye and Lochaber MP claimed the UK Government was prepared to put in jeopardy the Good Friday Agreement, but his comments drew a swift rebuttal from the Prime Minister who responded that the Government was "absolutely committed to the Belfast agreement".
Mr Blackford said: "The Foreign Secretary compared crossing the Irish border to going between Camden and Westminster, frankly you could not make this stuff up.
"This is a UK Government that is prepared to put in jeopardy the Good Friday Agreement. Does the Prime Minister agree with her bumbling Foreign Secretary who is making the UK a laughing stock?"
Theresa May responded: "Indeed we made sure that that commitment was included in the joint report that we agreed with the EU last December, so that commitment to the Belfast Agreement stands and we are committed to the Belfast Agreement and the institutions under the Belfast Agreement."
She added: "Of course I continue to stand by wanting to ensure that all parts of the UK continue to flourish. I think the best way of doing that is ensuring all parts of the UK remain in the UK."
Mr Blackford claimed there was a "power grab by Westminster" adding it was "no surprise" that the Scottish and Welsh Governments were putting forward continuity bills to stop it.
Mrs May replied: "He refers to this issue of devolved powers which are coming back from the EU, that was his reference. We have also given an absolute commitment to amending clause 11 and that commitment remains unchanged.
"The Chancellor of the Duchy of Lancaster has recently met with representatives of (the) devolved administrations, he put forward a further proposal for them which ensured that more powers are directly devolved to the Scottish and Welsh governments and in due course with the Northern Ireland executive and it was acknowledged that that was a significant step forward."
On the continuity bill issue, she said that the proposals being put forward were "unnecessary", adding: "It would be rather more helpful if he was to concentrate on reaching an agreement in relation to the withdrawal agreement because we want to ensure more powers are devolved to the devolved administrations, that's what we're going to deliver."