Nicola Sturgeon has challenged British Prime Minister Theresa May to set out her "plan B" for Brexit in advance of talks between the two leaders.
Scotland's First Minister warned against the "scare tactics" of talking up a no-deal Brexit scenario before a meeting with Mrs May in Edinburgh.
Ms Sturgeon said two key tests must be met by Mrs May in the Brexit negotiations before the October European Council.
A withdrawal agreement for an orderly transition must be secured, as well as a detailed statement on the future relationship between the UK and the EU agreed to avoid a "blind Brexit", she said.
Ms Sturgeon added: "A no-deal Brexit would be utterly unacceptable and deeply damaging, but by talking it up as a negotiating tactic there is a very real danger it becomes a reality.
"While the UK's focus is on the scare tactics of no deal, there has been no visible progress on securing a future relationship that protects trade in both goods and services.
"The prime minister promised a detailed statement on the future relationship with the EU alongside the withdrawal agreement, so parliament and the people would know where the UK is going. That promise must be kept.
"Parliament cannot be asked to make the decision on withdrawal without details on what the future relationship will look like.
"With the Chequers proposals falling flat, even if a withdrawal agreement can be secured, there is a very real risk that we end up with a blind Brexit, which will see the UK step off the cliff-edge next March without knowing what landing place will be.
"That would do as much harm to jobs, investment and the economy as a no-deal Brexit, and would leave the country directionless through the transition period.
"Given this lack of clarity and real concerns of no agreement, it is time the prime minister told us what her plan B is. We cannot have no deal and we cannot have a blind Brexit.
"The whole of the UK deserves answers from the prime minister and we cannot continue without a back-up plan."
Ms Sturgeon also called for "constructive and genuine" engagement with the Scottish government following a report by a committee of MPs that criticised UK government engagement with the devolved administrations.
She added: "The UK government has launched a power grab on the Scottish Parliament and now even a House of Commons committee says Whitehall takes little account of the realities of devolution in the UK.
"It cannot carry on like this and the UK government needs to start listening to the views of the people of Scotland, end the power-grab and start respecting the Scottish Parliament."