Donald Trump staged one of the most bizarre press conferences of his presidency in which he dismissed the entire US electoral system as corrupt and claimed that the election had been stolen from  him.

In a series of unsubstantiated allegations, he claimed he is being cheated out of re-election and warned there was a lot of litigation to come and suggested the ultimate decision on who had won the race would be determined by the Supreme Court.

The Republican incumbent alleged he was the victim of interference from “phony polls” as well as “big media, big money and big tech” after launching battles to stay in office.

In an extraordinary White House press conference late on Thursday, the President said: “If you count the legal votes I easily won. If you count the illegal votes, they can try to steal the election from us.”

The presidential election remains too close to call after polls closed on Tuesday, but former vice-president Mr Biden remains the favourite after winning three key battleground states.

Earlier, the former vice president had called for calm and patience to allow all the votes cast to be counted.

Pennsylvania was expecting to announce its result by the end of the day. If it goes to Mr Biden, so would the White House.