A HOLYROOD vote expected to back Nicola Sturgeon’s call for a second independence referendum will take place next Tuesday – the day before Theresa May launches the formal process to take the UK out of the European Union.

A majority of MSPs were due to support the First Minister’s motion on Wednesday to request the legal mechanism from the UK Government to allow a second independence ballot to be held.

But proceedings were dramatically suspended following the terror attack in London which happened as MSPs were taking part in the second day of the debate. Four people were killed in the incident including an unarmed police officer outside the Palace of Westminster.

With its flags flying at half mast, Holyrood’s business bureau decided yesterday morning not to immediately restart the debate, arguing it would be inappropriate to do so just as Westminster was resuming its daily business after the attack.

It is understood Holyrood’s five parties were split on the timing. The Scottish Tories, Labour and Lib Dems wanted to resume the Section 30 debate yesterday after First Minister’s Questions but the SNP and Scottish Greens opposed this.

The SNP originally proposed staging it next Thursday, the day after May invokes Article 50, but agreed to a Scottish Green party compromise offer to use its debate slot on Tuesday instead.

If, as is likely, Sturgeon wins the vote on Tuesday, the First Minister is highly likely to approach May in the final hours before the Prime Minister triggers Article 50 on 29 March to ask for the legal powers to stage the referendum.

May is also due to visit Scotland, before she invokes Article 50, on her tour of the UK to promote her Brexit strategy, again heightening tensions over Scotland’s constitutional future.

Security at the Scottish Parliament has been heightened since the Westminster attack with the First Minister yesterday saying the move was a precaution and there was no specific threat to the Parliament or Scotland.

A spokesperson for the FM said last night:“It was right that the debate and vote at Holyrood was postponed until next week, given the shocking events at Westminster. We will now wait until parliament has had the opportunity to vote before deciding on our next steps.”

May has said she will oppose any request for a section 30 order, saying the time is not right for another vote on independence.

Sturgeon has said she is willing to discuss the timescale but wants a referendum to take place before Brexit to ensure “Scotland’s interests are protected”.

The First Ministers set out plans for a new plebiscite after May failed to respond to the Scottish Government’s proposals to allow Scotland to remain in the UK and in the European single market.

The Tories, Labour and the Lib Dems all oppose her request for the order, though the Greens back it meaning that despite the SNP not having a majority in Holyrood the First Minister’s motion will be approved.

Scotland voted by 62 per cent to remain in the EU a result which has lead the Scottish Government to argue the country faces the prospect of being taken out of the bloc against its will.

Holyrood’s Presiding Officer Ken Macintosh took the decision to suspend business on Wednesday amid calls from some members for the debate to be stopped out of respect.

Conservative MSP Murdo Fraser had earlier asked for a halt to the debate but was told by deputy presiding officer Linda Fabiani it would continue.

Macintosh later told the chamber: “Members will be aware, and members of the public too will probably be aware from social media and other news reports they are following on their phones, that there’s been a serious incident at Westminster and Westminster itself has been locked down because of security concerns.

“I’ve certainly no wish to cause undue alarm here and security has been increased here, but I’m also aware and the business manager and I have discussed this, that the fact that our sister Parliament has had a serious incident is affecting this particular debate and is affecting the contribution of members and so it is for that reason we are deciding to suspend the sitting.

“We will resume this debate and we will be able to do so in a full and frank manner, but I think to continue at the moment would not allow members to make their contributions in the manner they wish to.”

Some MSPs had earlier walked out of the debate, with Conservative MSP Fin Carson tweeting: “I have left chamber. I can’t understand how this debate can go on. At least a suspension would have shown some respect.”