Liz Truss has branded Joe Biden a “weak president” as she attended the Republican National Convention in support of Donald Trump.

Speaking to Sky News’ James Matthews in Milwaukee, the former British prime minister criticised the current US president for his “rhetoric” around Mr Trump, who survived an assassination attempt at the weekend.

But unlike some right-wing politicians and commentators, she said she was “not prepared to draw the line” between Mr Biden’s language and the motivation of the gunman.

Mr Trump suffered minor injuries in the shooting at one of his rallies on Saturday, butan audience member was killed and two others remain in a critical condition in hospital.

Ms Truss said it was “absolutely appalling” and the presidential candidate was “just incredibly lucky, frankly, not to be killed”.

She said there “seems to have been a failure to properly protect” Mr Trump, as she called for a “full investigation into what happened”.

And she said it “makes everybody who is involved in politics fear what could happen”.

But Ms Truss said the man hoping to return to the White House after November’s US election “showed his strength and fortitude”.

She added it was “reminiscent” of another ex-prime minister, Margaret Thatcher, who still gave her party conference speech after the IRA bombed her hotel in Brighton in 1984

Asked whether Mr Biden held any portion of blame over the attempt on Mr Trump’s life, the former Conservative MP – who lost her seat at the last general election – said: “I do not support Joe Biden.

“I think he has been a weak president of the United States and I want Donald Trump to win.

“But clearly it is the responsibility of the putative assassin and the security services what’s happened.”

She went on: “I don’t like the rhetoric [from Mr Biden]… but I am not prepared to draw the line between one and the other.”