A second Scottish independence referendum should not be held before Brexit negotiations are completed, former minister Alex Neil has said.
Mr Neil told The Times newspaper he did not want to see a "premature referendum".
And he believes waiting to see the details of the deal the UK government agrees with the EU could "maximise" the prospect of independence.
Mr Neil served as health secretary under Alex Salmond and Nicola Sturgeon.
He revealed last month that he voted to leave the EU, against the strong pro-EU position of the party leadership, and claimed some other SNP MSPs had done so too.
'Maximise your chances'
Ms Sturgeon has said Scottish independence remains "firmly on the table" in the wake of the Brexit vote, with a majority of Scots voting to Remain in June's UK referendum.
And the Scottish government believes that people should "have the ability to consider the question of independence - and to do so before the UK leaves the EU - if it becomes clear it is the best or only way to protect our country's interests".
But Mr Neil told The Times: "You cannot realistically maximise your chances of winning a referendum for independence unless and until you know what the final Brexit deal is.
"The reality is that after the statement by (the EU's chief negotiator) Michel Barnier that the deal has got to be done in the next 18 months, physically it would be very difficult to get an independence referendum in that time.
"So realpolitik is kicking in anyway in terms of the timing, and realistically any referendum on independence is going to come after the deal is done."
Mr Neil, who stood down as social justice secretary in May, believes the best time for a second independence referendum would be after the next UK general election, scheduled in 2020.
"There's an argument that, with the likely result of an election in 2020, with a Tory government with an increased majority, that would be the best time to have a referendum," he told the newspaper.
"Let's not have a premature referendum which we might not win because we don't have all the answers."
Ms Sturgeon is due to publish options focused on keeping Scotland in the European single market, even if the UK leaves it, later this month.
Mr Neil has said his decision to vote Leave had been influenced by the growth of right-wing parties in Europe, the way Greece and Portugal had been treated by the bloc and the tone of the Remain campaign.
He wants two questions on the ballot paper of any future Scottish referendum.
He told The Times: "The first question is: 'Do you want Scotland to be an independent country? Yes or No'.
"The second question is: 'If a majority answer 'yes' to the first question, do you want an independent Scotland to reapply to join the EU?' I think you would get a very different answer."