British Foreign Secretary Boris Johnson has denied plotting to topple Prime Minister Theresa May, who has been weakened by the Conservative Party's disastrous election result.

Johnson tweeted that an article in the Mail on Sunday newspaper headlined "Boris set to launch bid to be PM as May clings on" was "tripe."

He said: "I am backing Theresa May. Let's get on with the job."

May is under pressure after the Conservatives lost their parliamentary majority in Thursday's election. The party is seeking support from Northern Ireland's Democratic Unionist Party to stay in power.

May's office said Saturday principles of an agreement had been reached, but the two sides later clarified that they are still talking.

Downing Street says it hopes to finalize the deal next week, after Parliament resumes sitting.