The Holyrood debate on a second independence referendum is set to resume on Tuesday following the Westminster attack.

Four people, including unarmed police officer Keith Palmer and the attacker, died and 40 were injured in the incident at the UK Parliament on Wednesday afternoon.

MSPs had been expected to vote on Wednesday to give First Minister Nicola Sturgeon the authority to seek talks with the UK Government over a fresh ballot. But following the London attack, the Scottish Parliament suspended the debate.

Presiding officer Ken Macintosh said the move was "an expression of our support for our sister Parliament" in London. He chaired a meeting of party business managers on Thursday morning to reschedule the debate.

The debate was called after Sturgeon's shock announcement last week that another independence referendum should be held as a result of the Brexit vote to leave the European Union.

On Wednesday, Sturgeon said it was right to suspend the debate as a "mark of respect and solidarity".

Business resumed on Thursday morning at Holyrood, where flags were flying at half-mast. A minute's silence was held at 9.33am in solidarity with parliamentarians at Westminster.

Speaking late on Wednesday, Sturgeon said: "My thoughts, as I'm sure the thoughts of everybody in Scotland tonight, are with people caught up in this dreadful event. My condolences in particular go to those who've lost loved ones.

"My thoughts are with those who've sustained injuries and we all feel a sense of solidarity with the people of London tonight.

"I have convened a meeting of the Scottish Government's Resilience Committee to review what is currently known about the incident at Westminster and also to review any implications for Scotland.

"It is important to stress that there is no intelligence of any risk to Scotland, but the police are ensuring that all precautionary steps are being taken as appropriate.

"And people should of course remain vigilant at this time, as at all times. But first and foremost tonight, all our thoughts should be with those affected by what is a horrific incident."

Police Scotland chief constable Phil Gormley revealed at a meeting on Wednesday afternoon that armed police had been deployed at several "key locations" across Scotland following the London attack.

The attacker, who has been identified but not named by police, was armed with two large knives. He drove a grey 4x4 vehicle into pedestrians on Westminster Bridge before crashing into railings at the Palace of Westminster.

He then stabbed to death 48-year-old PC Palmer before being shot by armed officers.