Scotland’s First Minister Nicola Sturgeon has led criticism of the UK government’s new Internal Market Bill, which has been unveiled.
The Internal Market Bill sets out how trade powers currently held by the EU will be shared out from 1 January 2021 onwards.
But many MPs are angry the legislation will amend key details of the UK’s Brexit agreement, which was approved by Parliament after the Conservatives won a landslide election victory in December.
The Permanent Secretary to the Government Legal Department, Sir Jonathan Jones, has already resigned in protect at the bill, which he says breaches the government's obligations under international law.
Northern Ireland Secretary Brandon Lewis admitted on Tuesday, 8 September, the bill would break international law in a "very specific and limited way."
Bob Neill, a Tory MP and chairman of the parliamentary justice committee, said: "Any breach, or potential breach, of the international legal obligations we have entered into is unacceptable, regardless of whether it’s in a ‘specific’ or ‘limited way’.”
Nicola Sturgeon tweeted that the Internal Market Bill was a “full frontal assault on devolution” and the Welsh government has also accused Boris Johnson of “stealing powers” from the devolved administrations in Wales, Scotland and Northern Ireland.
The Republic of Ireland's Deputy Prime Minister Leo Varadkar called Mr Lewis’s statement a "kamikaze" threat that had backfired.
Britain’s chief Brexit negotiator David Frost is due to meet his EU counterpart Michel Barnier in London on Wednesday to see if they can make progress before the 15 October deadline which Brussels has set for an agreement.
The EU says if Britain reneges on the Brexit deal which has already been agreed there cannot be a trade agreement.
French Junior Trade Minister Franck Riester said: "We need to make sure that our British partners respect their commitments."
The Irish border and the famous “backstop” affecting Northern Ireland was one of the biggest stumbling blocks to reaching a Brexit deal last year.
Now the government in London is proposing to change the deal it brokered last year, which meant Northern Ireland would effectively be treated as separate from the rest of the UK.
Mr Lewis said the new legislation would ensure businesses based in Northern Ireland would have "unfettered access" to the rest of Britain.
He claimed it would also address the contradiction whereby Northern Ireland would remain subject to EU rules on state aid for businesses but the rest of Britain would not.