London: The widower of British Labour MP Jo Cox says politicians who share content from extreme anti-immigration group Britain First content must be held accountable for their actions.

Brendan Cox's wife Jo was assassinated in June 2016 by a far-right extremist who yelled "Britain first" as he carried out a frenzied stabbing and shooting attack on the mother-of-two.

Newly-minted Liberal Senator Jim Molan, a retired major general, is refusing to apologise for sharing two videos on Facebook, which were originally posted by Britain First. They purport to show Muslim men in violent situations but their authenticity cannot be verified.

Senator Molan shared the posts on his private Facebook page a year ago. He has now closed down his private page but insisted that the only "unwise" aspect of his actions was that it had enabled his political opponents to accuse him of being a racist, a charge he has passionately denied.