EDINBURGH (Reuters) - A decision on calling a new Scottish independence referendum could be made within weeks, said a Scottish Greens lawmaker whose party is a key ally of Scottish First Minister Nicola Sturgeon.

Scotland's First Minister Nicola Sturgeon attends the Brexit debate in the Scottish Parliament Edinburgh Scotland, Britain January 17, 2017. REUTERS/Russell Cheyne

The timing of a potential new Scottish referendum - which polls say most Scots do not want - would be determined by the process of Britain’s exit from the European Union, said Ross Greer, a lawmaker and a key campaigner in the 2014 vote in which Scots rejected independence by a 10-percentage-point margin.

“We are working on a timescale now where Article 50 (which triggers Britain leaving the European Union) will be activated next month – that’s the timescale when it will almost certainly become clear whether there’s going to be a referendum or not. So that’s the timescale we should be working on to get our campaign up and running,” Greer told The Herald on Sunday.

Scotland - one of the United Kingdom’s four nations along with England, Wales and Northern Ireland - voted to keep its EU membership last June, but will leave the EU because the UK as a whole voted to do so. This means Scotland must have a fresh choice on its future, Sturgeon’s nationalists argue, if its wishes are not respected as part of the Brexit negotiations.

They have proposed a special deal for Scotland within Brexit which they say the British government has yet to consider.

Greer said he expected a successor to the “Yes Scotland” campaign from 2014 to begin to take shape in the coming weeks.

“We will know in the next few weeks how to (take) that a step further and in the next few weeks I expect moves will be made to form what could be that organization,” he was quoted as saying.

The Scottish Greens’ six seats in the Scottish parliament would complete the 65 seats for a majority that Sturgeon’s Scottish National Party (SNP), with 63, would need to pass legislation on a referendum.

Technically the British parliament, which is sovereign, could block another referendum on independence. But to do so would likely provoke a constitutional crisis if opinion polls were to show most Scots favor a ballot.

While Sturgeon’s party has independence as a long-term goal, she will also avoid calling a referendum unless there is clear evidence she would win. So far, despite unhappiness about Brexit in Scotland, opinion polls show that support for independence is still at around 45 percent as it was in 2014.

Greer said the calling of such a vote would have to be a joint decision for the SNP and Greens.