Nationals MPs have launched a scathing attack on Prime Minister Malcolm Turnbull's sex ban, describing the move by the senior Coalition partner as "bonkers".

The response of furious Nationals MPs built up to an extraordinary response from Nationals leader Barnaby Joyce on Friday, who labelled Mr Turnbull's comments as "inept" and only "caused further harm".

Maverick MP George Christensen became the latest National to criticise the move on Friday, claiming no one cares about "who is shagging who" in Canberra.

"The bonk ban is bonkers," he said. "And it shows that the whole attack on Barnaby Joyce is driven by one thing: sex."