Alex Salmond sees autumn 2018 referendum
Former first minister Alex Salmond has indicated a decision on whether to hold a new independence referendum could come within weeks.
He said the UK government's response to Scottish plans to protect trade with Europe would be crucial.
Mr Salmond, the SNP's international affairs spokesman at Westminster, said a rejection of the plans would probably result in an autumn 2018 referendum.
The UK government has said it will seek a deal for "the UK as a whole".
Speaking on the BBC's Sunday Politics Scotland programme, Mr Salmond said: "The UK government has still to respond to Nicola Sturgeon's compromise proposal.
"That's going to come over the next few weeks and once that's done - if they reject it as many people predict - then we'll know that they're not interested in the voice of Scotland.
"As Nicola Sturgeon has said it is (then) very likely there will be another independence referendum."
In an initial response to the Scottish government's plan to continue open trade with the EU, published at the end of 2016, a Downing Street spokesman said the government welcomed it and would "look closely" at it.
But the spokesman made clear that Prime Minister Theresa May is determined to deliver a UK-wide Brexit and did not believe there should be a second referendum on Scottish independence.
He added: "The government is committed to getting a deal on exiting the EU that works for all parts of the UK - which clearly includes Scotland - and works for the UK as a whole.
"The best way for that to be achieved is for the government and devolved administrations to work together."
Mr Salmond said he thought the degree of progress being made in Brexit talks would be clear before a vote on Scottish independence took place.
He said: "If there is another independence referendum then the timescale I would have said would be the autumn of next year."
"If you're talking about a referendum in about 18 months time, by then the negotiations will be crystallised.
"You'll be able to tell what the deal - or no deal - is going to be.
"And certainly that's after the timescale the government was talking about this week about bringing the deal or non-deal back to the House of Commons for a vote."
Scottish Labour said the supporters of independence had still to answer detailed questions such as which currency an independent Scotland would use.
The party's business manager James Kelly added: "Scotland is divided enough, the SNP should rule out another divisive independence referendum and focus on improving our schools and hospitals.
"Labour believes that together we're stronger, and that is why we oppose a second independence referendum."