Nicola Sturgeon is to raise Scottish concerns over Brexit in a meeting with chief EU negotiator Michel Barnier in Brussels.
Scotland’s first minister has called on the UK government to offer more clarity on its plans for the future relationship with the EU.
And she has demanded that it “engage properly” with devolved governments across the UK.
The UK government has declined to comment.
Ms Sturgeon wants to stay inside the customs union and single market, which she sees as “the best possible outcome from Brexit, short of continuing EU membership”.
Mr Barnier expressed frustration at the state of the negotiations last week, claiming that the UK was playing “hide-and-seek” by refusing to spell out exactly what it wants.
In a strongly worded speech in Lisbon, Mr Barnier stressed that “time is and will remain tight”, and called for progress to “speed up” if details of the future relationship are to be agreed before the Brexit date.
The Scottish and UK governments have been in dispute over what should happen to powers currently held by Brussels after MSPs refused to give their consent to the EU Withdrawal Bill.
Earlier, Scotland’s Brexit minister Michael Russell told BBC Radio Scotland’s Good Morning Scotland what would be discussed at the meeting.
He said: “It is another opportunity to explain where we are, why we believe that membership of the single market and the customs union is absolutely essential for Scotland.
“While I would certainly love to stay in the EU – and I think that’s the best option – the only acceptable next option would be single market and customs union membership.
“Once you go beyond that into a free trade treaty, into the WTO role scenario, you’re in a terrible situation. So it’s important that Brussels understands that.”
Ms Sturgeon is to hold the meeting while in Brussels for the official opening of the expanded Scotland House, a hub for Scottish businesses in Europe.
She said: “People and businesses are desperate for clarity on Brexit, but with just months to go before the withdrawal agreement has to be signed, the UK government still cannot agree a position.
“This damaging uncertainty could come to an immediate end if only the UK government would put jobs and living standards first and agree to continuing single market and customs union membership – for Scotland and the whole of the UK.
“Whatever the outcome of the Brexit negotiations, we are committed to continuing our collaboration, our friendship and our partnership with other European countries.
“Increasing our presence across the EU is a significant part of maintaining those relationships, and the newly-expanded Scotland House has a major part to play in representing Scotland across the whole of the EU.”
The Scottish Conservatives’ constitution spokesman Adam Tomkins said of the first minister’s visit: “Rather than working with the UK government to do a deal on Brexit, she’s chosen to take a pointless trip to Brussels.
“It’s becoming ever more obvious that Nicola Sturgeon wants to create a political crisis to justify her continued push for independence.”
Scottish Liberal Democrat leader Willie Rennie said: “I hope that Nicola Sturgeon uses her visit to Brussels to reflect on the damage caused by breaking up political unions.”
Neil Findlay, Scottish Labour’s Brexit spokesman, said: “Brexit simply shows how difficult it is to leave a political union – even one less integrated than the UK.”
Sturgeon takes Brexit concerns to Brussels}