A second independence referendum is a "matter of when – not if," Nicola Sturgeon has told Prime Minister Theresa May.

Following the SNP's fourth consecutive victory in the Scottish Parliament election, the First Minister spoke with Boris Johnson on the phone on Sunday.

The party won 64 seats, falling only short of an absolute majority, but with the Scottish Greens winning eight seats, the Scottish Parliament now has a pro-independence majority.

"The First Minister talked to the Prime Minister this afternoon, and thanked him for his congratulations on her re-election," a spokesperson for Sturgeon said on Sunday.