In a short tweet, Mordaunt said she intends to stand in the race in order to "unite" the Tory Party, based on backing from many party members who want to put an end to Tory differences and move forward to a new stage.

Mordaunt, who held several ministerial posts in former governments, is the first candidate to officially enter the race.

Labour and other opposition parties have called for an immediate general election.

UK Prime Minister Liz Truss on Thursday resigned just after 45 days in her post.