Scots should be given the opportunity to vote again on independence before the next Holyrood elections in 2021, First Minister Nicola Sturgeon has said.

In a statement to MSPs, she said: “A choice between Brexit and a future for Scotland as an independent European nation should be offered in the lifetime of this Parliament.

“I can confirm that the Scottish Government will act to ensure that the option of giving people a choice on independence later in this term of Parliament is progressed.”

She said Westminster has failed to protect Scotland’s interests and that the Scottish Government is taking steps to rectify that by introducing legislation to set out rules for another vote.

The First Minister said: “Throughout this, the Scottish Government have worked tirelessly to help find the best way forward for all of the UK.

“Whatever Scotland’s constitutional status in the future, it will always be in our interests for these islands to have the closest possible relationship with the EU.

“We have done everything possible to help avert the Brexit crisis for the whole UK. And we will continue to do so.”

She added: “The Westminster system of government does not serve Scotland’s interests.

“And the devolution settlement, in its current form, is now seen to be utterly inadequate to the task of protecting those interests.”

Wednesday’s statement was the “first available opportunity” for the First Minister to update MSPs since the EU granted a six-month extension to the Article 50 Brexit process.

A Number 10 spokesman said on Tuesday that Theresa May’s stance on the issue of a second Scottish referendum “has not changed” – with the PM having previously made clear her opposition to such a ballot.

Scottish Conservative interim leader Jackson Carlaw said: “Whatever the First Minister says about being ‘inclusive’, her statement is inherently divisive.

“Astonishingly, the way Nicola Sturgeon thinks we can come together is for Scotland to be plunged into another divisive referendum within the next 18 months.

“That is frankly absurd.

“The SNP’s plan is clearly to divide families, workplaces and communities all over again, and for the foreseeable future. That is not what the majority of Scotland wants.

“People have had enough of constitutional politics and division. Yet, with the SNP, more of this is now inevitable.”

Scottish Labour leader Richard Leonard said: “Nicola Sturgeon is using her office as First Minister to put the interests of the SNP before the interests of our country.

“Her statement today is not about Brexit, this is about Nicola Sturgeon trying to pacify her party members and back benchers ahead of the SNP’s conference.

“The chaos of Brexit throws into sharp relief the challenges of leaving a political and economic union.

“The Brexit shambles has only confirmed our belief that we would be far better governing ourselves.

“Leaving the UK would lead to unprecedented austerity for Scotland’s public services.

“The political dividing line in Scotland is clear: investment with Labour with a focus on fixing our public services and economy or another decade of austerity with the SNP and the Tories with a focus on divisive and destructive nationalism.”

Scottish Greens parliamentary co-leader Alison Johnstone said: “The Scottish Greens have always believed that Scotland’s future should be in Scotland’s hands, as an independent nation at the heart of Europe.

“The Brexit shambles has only confirmed our belief that we would be far better governing ourselves.

“The vision currently being considered by the SNP looks more like the failed economic model of the UK, a vision which has led to cuts to public services and increasing child poverty, than the bold vision for independence the Greens campaigned for and believed in.

“The First Minister also announced the establishment of a citizen’s assembly. We welcome this move, but this body cannot simply be a talking shop. We will put pressure on the Scottish Government to ensure that this body is listened to and shapes government policy.”

Scottish Secretary David Mundell said:  “People in Scotland voted decisively in 2014 to remain part of the UK, on a promise that the referendum would settle the issue for a generation.

“Instead of respecting that result, Nicola Sturgeon continues to press for divisive constitutional change when it is clear that most people in Scotland do not want another independence referendum. The UK Government will stand up for them.

“Nicola Sturgeon needs to listen to the views of the Scottish people and concentrate on improving Scotland’s economy and schools, not continually trying to orchestrate upheaval and division.”