The prospects of a Brexit deal with the EU appear to be “promising” after negotiations between Boris Johnson and Leo Varadkar over the Irish border, Nicky Morgan has said.

A day after the British prime minister signalled the possibility of a U-turn on his plans, the culture secretary said the “mood music … seems positive, but clearly there are lots of details to be worked out.”

She told BBC Radio 4’s Today programme: “There are strong views on all sides and I imagine we’ll all find out around the EU council next week exactly what has happened between the two sides.”

On Friday, EU sources said Johnson had conceded there could not be a customs border on the island of Ireland – a critical step away from his previous position. Officials are continuing talks in Brussels over the weekend after the EU’s chief negotiator, Michel Barnier, gave the go-ahead for intensive negotiations to start.

However, Morgan would not be drawn on details of the discussions because “there are subtle nuances with all of these things”.

She added: “It’s a question of what is negotiated between the parties and obviously it also has to satisfy people living in Northern Ireland, who are very much at the heart of all of this, and to be approved by members of parliament.”

The Democratic Unionist party and the European Research Group of rightwing Conservatives issued statements promising flexibility, keeping hope alive that Johnson could find support for a new offer in the House of Commons.

But the prime minister faces a frantic race to push through a deal before 31 October. On Friday, he twice refused to deny Northern Ireland could stay in the EU’s customs territory after Brexit.

During a briefing of EU ambassadors on Friday, Barnier did not go into the details of the UK’s new position. But he informed the diplomats that his two-hour breakfast with UK’s Brexit secretary, Stephen Barclay, had been notable for the apparent pivot by the British government.

One EU source said: “The UK has accepted that there is not a deal that involves a border on the island of Ireland – that is a big break from what they were saying. Now the key is for them to lay out how their new position over the weekend.”

Morgan also said reports that Johnson was preparing to fight a general election on a no-deal platform if he were unable to get an agreement were “wide of the mark”.

She added: “The prime minister has always been clear that a deal is infinitely preferable and that is what we want to see.

“These talks with our EU friends and neighbours are obviously at a very delicate stage. I think it is incumbent on all of us to stand back from briefings and speculation and just allow these talks to happen.”