Washington, Oct 1 (IANS): US President Donald Trump has said a far-right group should "stand down" and let law enforcement do its work, after his refusal to explicitly condemn the group in a TV debate sparked a backlash.

Trump said "I don't know who the Proud Boys are", a day after urging them in the election debate with Joe Biden to "stand back and stand by".

Proud Boys members called his debate comments "historic" and an endorsement, the BBC reported on Thursday.

Biden said Trump had "refused to disavow white supremacists".

The exchange came during the first of three televised debates between the two men ahead of the November 3 election. The debate descended into squabbling, bickering and insults, with US media describing it as chaotic, ugly and awful.

The commission that regulates the debates said it would introduce new measures for the next two to "maintain order". Trump said they should get a new anchor and a smarter Democratic candidate.

Not much was gleaned on policy and although one snap poll on the debate gave Biden a slight edge, other opinion polls suggest 90 per cent of Americans have already made up their mind on who to vote for and the debate may well have made little difference.

Biden has consistently led Trump in national polls, but surveys in so-called battleground states suggest the vote could still be a close contest.

Moderator Chris Wallace asked whether the president would condemn white supremacists and tell them to stand down during protests. These have flared this year over the issues of police killings and racism.

"Sure, I'm willing to... but I would say almost everything I see is from the left wing, not from the right wing," Trump said.

Biden twice said "Proud Boys" when the president asked who it was he was being told to condemn.

The president said: "Proud Boys - stand back and stand by. But I'll tell you what... Somebody's got to do something about antifa and the left because this is not a right-wing problem."