NICOLA Sturgeon has welcomed a breakthrough in the first phase of Brexit talks but warned that the "devil is in the detail" of the deal.

Scotland's First Minister said "things now get really tough" after the European Commission announced that ''sufficient progress'' had been made to move negotiations on to the next phase.

Intensive talks have been continuing after the Northern Irish Democratic Unionist Party (DUP), which props up the minority Conservative Government in Westminster, scuppered a deal aimed at resolving the Irish border issue on Monday.

READ MORE: Brexit talks make 'sufficient progress' to move onto second phase of negotiation

Prime Minister Theresa May said the fresh deal would guarantee the rights of three million EU citizens in the UK and ensure there would be no hard border between Northern Ireland and the Republic.

Sturgeon has said there is an opportunity for those in opposition to unite behind a "soft'' Brexit, which would see the whole of the UK stay in the single market and customs union.

Responding to news of the deal on Twitter, she said: "Move to phase 2 of talks good - but devil is in the detail and things now get really tough.

"If Brexit is happening (wish it wasn't) staying in single market & customs union is only sensible option. And any special arrangements for NI must be available to other UK nations."

She added: "An aside - a UK government that is able to say that come what may, it will avoid hard borders with Ireland/NI after Brexit can never again tell Scotland that independence would mean a hard border between Scotland and rUK."

Scottish Conservative leader Ruth Davidson wrote on Twitter: "Good news on moving to phase 2 in EU negotiations. Now, let's talk trade."