Scotland’s first minister said on Tuesday that the devolved Scottish parliament would not consent to legislation necessary to keep Britain’s Brexit plans on track, presenting another thorny issue for the government to surmount.

Prime Minister Theresa May’s government on Monday indicated that it would go no further in offering concessions to Scotland, Wales and Northern Ireland, who are concerned that they will lose powers in a constitutional realignment after Britain leaves the European Union.

The United Kingdom’s devolved nations do not have a veto on Brexit legislation, but ignoring their wishes risks worsening already strained relations, stoking nationalism in Scotland, and further complicating the already-difficult withdrawal process.

“I will not sign up to something that effectively undermines the whole foundation on which devolution is built,” Nicola Sturgeon, whose party supports independence for Scotland, told BBC radio. As things stand, her government could not recommend consent for the bill, she said.

Cabinet minister David Lidington said on Monday that most currently devolved powers would now automatically stay in Edinburgh, Cardiff and Belfast, the devolved nations’ capitals, after Britain leaves the European Union.

But the British government would make exceptions if it believed that would damage the UK as a whole, he said, comments that raised hackles in Scotland and appeared to overturn progress made between the sides last week.

The British government needs a deal before the summer in order to pass the European Union (Withdrawal) Bill in Britain’s national parliament. The bill will formally sever the UK’s ties to the EU and “copy and paste” EU legislation into British law.