Michael Gove is to meet Ireland’s deputy prime minister at the weekend for talks as tensions mount over Brexit and the Irish border.

The chancellor of the duchy of Lancaster’s meeting with Simon Coveney in Cambridge will take place just before Boris Johnson’s visit to Dublin on Monday, when he will meet the taoiseach, Leo Varadkar, for the first time since becoming prime minister.

Both meetings come as the shadow Brexit secretary, Keir Starmer, said he was deeply concerned about reports that the UK was backsliding in Brussels talks regarding commitments on Irish matters in the joint report signed by Theresa May and the EU in December 2017.

The Brexit secretary, Stephen Barclay, declined to deny an RTE report that the UK had indicated it wanted to replace a promise on “frictionless trade” with the wording “frictionless as possible”, and wanted “legally operable” commitments changed to “aspirational measures” when challenged by Starmer in the House of Commons on Thursday.

There were also reports in the Irish Independent on Thursday of an 11-page UK paper, marked “official-sensitive”, suggesting a “new common rule book” could be shared between Ireland and the UK on goods, in effect meaning Ireland would have to leave the single market.

Starmer told the Guardian: “The 2017 joint report was the foundation of a deal with the EU that would avoid a hard border in Northern Ireland. The Brexit secretary’s refusal to stand by that agreement is deeply concerning and reveals the government’s willingness to backtrack on the solemn commitments it made to the people of Northern Ireland two years ago.

“It is yet more evidence that the government is not really seeking to negotiate a deal with the EU. That is why we must continue to do all we can to stop Boris Johnson’s plan for a no-deal Brexit.”

Barclay told Starmer: “There is no rowing back from the Belfast/Good Friday agreement, that’s an area of common accord between us.”

Starmer reminded him he was asking him about the 2017 joint report, not the 1998 peace deal. “I asked a careful question and I got a careful answer and it wasn’t to confirm full commitment,” he said.