Welsh first minister says PM needs to ensure she engages with population over effects of Brexit as she sets off on UK tour

Theresa May will face demands from the leaders of the UK’s devolved governments to radically rethink her approach to the union as she begins a four-nation tour before beginning Britain’s exit from the EU.

Downing Street said the visits, which will begin on Monday in Swansea with the Welsh first minister, Carwyn Jones, would ensure the government was “engaging and listening to people from right across the nation” before triggering article 50.

Jones, however, told the Guardian that May’s “tin ear” on issues of devolution would mean Westminster will soon replace the EU at the heart of voters’ frustrations at having their affairs managed from afar.

He said there was a battle looming over granting greater devolved powers, backed this weekend by the former prime minister Gordon Brown, which the government had to take seriously or risk fracturing the country.

“If they are not careful, people’s sense of disengagement with Brussels will simply attach itself to London,” he said. “They are giving the impression sometimes that they do not listen .

“And what kind of message is that to the people of Wales? We need to see there is a dividend in being a devolutionist government that supports the union and we don’t see that dividend.

“Otherwise people in Wales are going to start saying, well, the government is listening to the Scots, we need to be like them. And that’s a dangerous path for the UK.”

The Welsh intervention adds to disquiet in Scotland, where the first minister, Nicola Sturgeon, repeated demands on Sunday for a second independence referendum to pave the way for the country to remain in the European single market.

In what appeared to be a softening of her position ahead of a potential meeting this week, she added she was prepared to be flexible on the timetable and delay until 2019.

Government sources denied the visit was in any way a response to the ratcheting up of tensions in the union by Sturgeon’s demands for a second referendum, which May has said she will not permit.

During her visit, May will underscore the value of collaboration between the UK government and devolved administrations as she launches a “ city deal” for Swansea that has attracted investment worth£1.3bn .

No 10 said the deal would pave the way for 9,000 new jobs and new infrastructure in the bay area, including a waterfront “digital district”.

“The deal is a great example of what can be achieved when the UK government , the Welsh government and local authorities work together to secure a deal that benefits the city and the whole of Wales,” May said ahead of her visit.

A Downing Street source said she would be unlikely to make any commitments on devolution during her visit on Monday, insisting it had been long planned. “We’ve been listening the views of all different regions through the joint ministerial council,” the source said.

“On the powers coming back from Brussels, we have said that first it will come back to Westminster. And then when it is appropriate to devolve further, then we would. That decision will be taken at a later date.”

Jones said there was much the Welsh and Northern Irish governments were still in the dark over, including which courts would arbitrate on state aid and any new regulations covering devolved arrangements, such as agriculture, which had previously been the domain of the European court of justice.

Welsh ports could also suffer, he said, if the government allowed a softer border arrangement between Northern Ireland and the EU than the rest of the UK, meaning Irish exporters would be far more likely to use Northern Irish than Welsh ports.

“We are going to end up in court on that unless we can sort this out,” Jones said. “Our devolution settlement says agriculture is devolved, full stop. We are never going to accept Brussels is replaced by London. Their heads are not around this yet.

“There was as much frustration on the doorstep about the UK government as about the EU [during the referendum]. At the end of the day, it’s not as if Westminster and Whitehall were fantastically popular.”

Jones’ demand that Downing Street look again at the complex nature of trading arrangements after Brexit echoed the concerns expressed by the former prime minister Tony Blair in an interview over the weekend.

Blair said even he had underestimated the seismic changes that would need to take place to replace the European single market. “I didn’t understand how complicated this is going to be,” he told the BBC’s Andrew Marr Show.

“If they’re going to try and deliver exactly the same benefits as we have now in the single market and customs union, this is an endeavour of unparalleled complexity.”

Blair, who launched his own centrist institute last week, said he believed leave voters would eventually begin to question whether control of EU immigration was worth the upheaval.

“People start to think is this really going to be the thing that is going to be important. And then when you look at Scotland you see another strain on the constitution of the country as a result,” he said.

On Sunday, Sturgeon hinted she was prepared to continue compromise talks with the UK government, saying she was willing to have a “reasonable” discussion with May to delay a Scottish independence referendum, but insisted it could not be put off for long in the face of Brexit.

“[May] said she does not agree with that timescale,” she told Peston on Sunday. “I think it is for her then to say what timescale she thinks would be appropriate and I’m happy to have that discussion within reason.

“If she’s talking in the spring of 2019, a bit later perhaps than I was suggesting, there may be some room for discussion around that. But it seems to me to be just fundamentally unfair for a UK government, with Brexit having sunk the ship, trying to puncture Scotland’s lifeboat as well.”

Sturgeon added that a delay until after the next Scottish parliamentary elections in 2021 would not be acceptable. “I don’t think that is reasonable because by that point Scotland has been taken out of the EU, two years have elapsed,” she said.

“Presumably there is divergence opening up between the rules of the European Union and the single market and where the UK is going. I think it then gets much harder for Scotland to seek a different course.”

Ruth Davidson, the leader of the Scottish Conservatives, repeated her opposition to a referendum on Sunday and said it was wrong to consistently portray the Scottish National party as the voice of Scotland.

“The SNP is not Scotland and they are acting against the majority wishes of the people of Scotland in putting forward their proposition on Monday,” she said.

“There are people right across Scotland, many, many thousands of them, that are so thankful for the prime minister to say let’s take a pause on this.

“We have asked basic questions on things like currency, on things like a central bank, on things like whether we would even rejoin Europe as a full member, and Nicola Sturgeon seems unable to commit to that.”

Labour’s Scottish leader, Kezia Dugdale, has said her party will oppose an independence referendum at the vote at the Scottish parliament on Wednesday, saying her party wanted to wait for the outcome of the Brexit talks.

“At the moment, there is not a clear choice for Scottish voters,” she told Sky’s Sophy Ridge on Sunday. “If we have to have another referendum … we have to make sure people understand what they get either way.”

Jones will host a summit in Cardiff later this month on Labour’s approach to a new UK constitutional settlement, as outlined by Brown’s speech on Saturday. Dugdale and regional mayors will be in attendance, but not the Labour leader, Jeremy Corbyn.

The first minister said Corbyn was not opposed to the idea, but was happy to let others in the party take the lead. “We want to put forward something that recognises the strong identities of the nations of the UK and a common purpose,” he said. “This is something we can put forward to ensure the stability of the UK as a party.”