A BILL to establish the rules for an independence referendum will be introduced later this week into Holyrood.

Scottish Brexit Secretary Michael Russell is due to unveil the legislation which is expected to be passed by MSPs by the end of the year.

The move follows a statement by the First Minister to the Scottish Parliament last month when she advanced plans for a new vote within the current parliamentary term, which ends in May 2021.

Nicola Sturgeon said she would not seek a transfer of powers from Westminster to hold the vote before the Bill was introduced, but would do during or after the Bill’s passage and “at an appropriate point”.

“By making progress with primary legislation first, we will not squander valuable time now in a stand-off with a UK Government that might soon be out of office,” she told Holyrood on April 24.

“We will seek agreement to a transfer of power at an appropriate point during or shortly after the Bill’s passage, on the basis that it will be exercised when this Parliament – and no other – considers it right to offer the people of Scotland a choice.”

Theresa May’s government has said it will refuse any Section 30 order from the Scottish Government to hold a second independence referendum, claiming the result of the 2014 vote in which 45% of Scots voted in favour of independence and 55% against must stand.

But the First Minister has underlined that the SNP stood on a manifesto at the 2016 Holyrood elections of backing a second vote on independence if there was a “change in material circumstances” such as Scotland being taken out of the EU despite voting to remain.

Scotland voted to stay in the bloc by 62%.

Meanwhile, the UK is under further constitutional strain in Remain-voting Northern Ireland. Sinn Fein is pressing the Irish government to call a unity referendum following the results of a RTE exit poll showing 65% of voters back a united Ireland. The island has been divided into two separate jurisdictions since 1921.

Party vice president Michelle O’Neill said now is the time to “prioritise planning for reunification”.

“The issue of Irish unity has taken on a new dynamic because of Brexit, which has again showed the failure of partition and division,” she said. “Demographics are changing and so too is the political landscape across Ireland. All parties that see the value of reunification and hold to the ideal of unity must act to begin a national conversation.”