Nicola Sturgeon has warned time is running out for the Prime Minister to "heed the voice of Scotland" ahead of key Brexit talks.
Scotland's First Minister urged Theresa May to take proposals from the devolved administrations seriously when she chairs a "crucial" meeting of the Joint Ministerial Committee (JMC) in Cardiff on Monday.
On the agenda will be a Scottish Government paper setting out options to keep Scotland in the European single market even if the UK leaves, reflecting the majority Remain vote north of the border.
Proposals to remain in the single market have also been put forward by Welsh first minister Carwyn Jones and Plaid Cymru leader Leanne Wood.
A UK Government spokesman insisted that the proposals from the devolved administrations were being "studied carefully".
Speaking before the meeting, Ms Sturgeon said it was "one of the most important since the result of the EU referendum seven months ago".
"It comes at a crucial juncture, with the clock ticking down to the triggering of Article 50 and with, so far, no sign whatsoever that the UK Government is taking Scotland's position remotely seriously," she said.
"The JMC meeting in Cardiff is another chance for the Prime Minister to heed the voice of Scotland and those of the other devolved governments – and she must take the opportunity to do so."
Ms Sturgeon said a hard Brexit as proposed by Mrs May could be "economically disastrous" for the UK and "catastrophic" for jobs, investment and living standards in Scotland.
She added: "The Prime Minister has also warned that it could herald a new economic model which leaves the UK as a low-wage, deregulated country where job insecurity is high and where workers' rights and social protections are stripped away.
"That is the stark reality of the Tories' vision for the country and it is one that will fill most people in Scotland with dread.
"We have compromised by publishing detailed proposals to keep Scotland in the European single market even if the rest of the UK leaves.
"Those compromise proposals are formally on the agenda for this meeting, and so the Prime Minister tomorrow has a chance to show she is serious about her pledge to properly consider those proposals.
"So far, the Tories' words on respecting Scotland's voice and the UK being a partnership of equals have amounted to nothing more than empty rhetoric.
"But the Prime Minister should be in no doubt that time is fast running out for her to show that Scotland's needs and interests can be accommodated through the UK Brexit process."
Ms Sturgeon has warned that Mrs May's plans to take the UK out of the single market ''undoubtedly'' makes a second referendum on Scottish independence more likely.
A spokesman for the UK Government said: "We have been determined from the start that the devolved administrations should be fully engaged as we form the UK's negotiating position for leaving the EU. The JMC process gives Scottish Government ministers direct access to the UK Government as we plan our EU exit.
"All proposals from the devolved administrations are being studied carefully.
"We are focused on getting the right deal for Scotland and the UK as a whole. That means the best possible access to the EU market for British businesses. It also means ensuring a strong future for our United Kingdom, which the Scottish Government's own export figures show is worth four times more to Scotland's economy than the EU single market."