A US senator has warned that Russian cyber operatives are "setting up shop" in Scotland to foment support for a second independence referendum.

Senator Angus King told a Washington hearing into Russian interference in last year's US presidential election that Scotland was also on the Kremlin's target list.

He told the Senate Intelligence Committee: "We know the Russians were involved in the French election. We know that they were involved in the German elections. We are now learning they were involved in the separation of Spain.

"And my understanding is they've set up shop in Scotland which is talking about an independence vote from Great Britain. This is a sophisticated worldwide strategy. It hasn't stopped and it won't stop."

On Wednesday night a senior MP demanded answers from Facebook on whether Russians were using the social network to cause discord in Scotland.

Damian Collins, the chairman of the digital, culture, media and sport committee, said he would press the company on the matter as part of the committee's investigation into the impact of fake news on British politics.