The SNP should be able to call a "snap referendum" on independence during the next Scottish parliament, one of the party's MPs has said.
Martyn Day, the MP for Linlithgow and East Falkirk, said the option of a second independence referendum "needs to be kept open" in the party's manifesto for next year's Scottish election, where the SNP is expected to increase its majority.
Before last September's independence referendum, SNP leader Nicola Sturgeon said the vote would be "once in a lifetime" but has, more recently, said there will be another independence referendum "when the Scottish people decide".
David Cameron ruled out a second referendum last month, saying: "I think it is important that a referendum is legal and properly constituted and that is what we had, and it was decisive, so I do not see the need for another one."
But, speaking in a webcast for Independence Live, Day said the SNP should have the option to call a referendum as early as next year, after the anticipated UK-wide referendum on EU membership.
"I think there will be another referendum, I'm just not sure when," said Day. "I think it needs to be kept open in the manifesto."
"We know the faultlines we failed on in the last one," he continued. "We didn't win [over] enough of the elderly pensioners, particularly older women, we didn't convince enough people of the currency arguments or the business scares. We know that's what we have to address.
"Once we address that, possibly combine it with a divisive EU referendum that could see Scotland and England voting differently, we might have the grounds for a snap referendum."
Day added that a second referendum can only be won by gaining the support of No voters by convincing them they were "betrayed" in September.
"It's also [about] convincing our friends," said Day. "Getting people who were No or reluctant Nos to make the decision that, it's not so much they made the mistake, but for them to feel that they were conned, that they were betrayed, and they have to take the next step. That's when we'll win."