Al Gore urged supporters of Donald Trump to reject violence if the president loses the election to challenger Joe Biden. The former vice president appealed to all sides to respect the election process, as hundreds of thousands of postal votes continue to be counted. Mr Trump has claimed Democrats are trying to steal the election and on Friday reiterated allegations of voter fraud, without providing evidence. "I've heard the president say that if he doesn't win there may be this, that and the other - nobody should be inciting violence, that's dishonouring the mandate of the American people to make this choice," Mr Gore told NBC News. "I would urge all Americans, particularly those that might be tempted to follow the direction the Donald Trump pointed in earlier today, to reject that approach." Elements of Mr Trump's support base have protested at voting centres and there were dozens of arrests in Seattle, Minneapolis and Portland on Thursday evening. The president has demanded the vote be stopped in states he leads in - and repeatedly alluded to unrest and violence, without directly calling for it. Mr Gore, who served as vice president for eight years under Bill Clinton, reiterated that no claims of voter fraud have been substantiated. "Donald Trump has come out, without any evidence whatsoever, to allege that because he's losing it must be fraudulent," he said. "I wish he wouldn't do that. "I hope that he will find a way to fall in behind those of us who are trying to bring the country together. "If Donald Trump does face a situation where the votes are all counted and he turns out not to he successful, I would urge him to do the right thing - and yes it would astonish a lot of people - but it would be good for our country." Al Gore lost the US presidential election in 2000 to George W Bush after a Supreme Court ruling over vote counting ended five weeks of political turmoil. He said: "This is a completely different election from the one 20 years ago. Joe Biden has multiple pathways to secure his victory and of course I'm for him and I'm hoping that will be the case very soon. "But the most important principal that I defended 20 years ago, that Joe Biden and many others are defending, is let's count every legally cast vote and obey the will of the American people. "I looked at the people standing in line to vote in the middle of a pandemic - some of them waiting in line 10 or 11 hours in some cases - and the determination of the American people... to have the largest turnout in the entire history of our country. "They're heroes and they're realising the promise of America."