Prime Minister Scott Morrison has defended a plan for Malcolm Turnbull to travel overseas on behalf of the government as he rejects reports his relationship with his predecessor has soured.

Mr Turnbull will attend an oceans conference in Bali on October 29-30 in the face of criticism from some government backbenchers, including former deputy prime minister Barnaby Joyce.

When informing Indonesian President Joko Widodo he was unable to attend, Mr Morrison said the offer for Mr Turnbull to go instead was warmly received.

He said Mr Turnbull’s strong relationship with President Widodo was a key factor in the call.

“I don’t think Malcolm’s hanging around looking for a trip to Bali,” Mr Morrison said in Canberra on Wednesday.

“Former prime ministers continue to have a role to play to serve our country, when and where they’re able to do that.”

News Corp on Wednesday reported Mr Morrison “was done” with the former PM because of his failure to help campaign in the Wentworth by-election.

The Prime Minister’s office refutes the claim.

On Tuesday, Mr Joyce said the decision to send Mr Turnbull to the Bali conference was “pretty wild”, especially given the former PM refused to campaign for Liberal candidate in Wentworth, Dave Sharma, and now the Coalition has lost its majority.

Independent Kerryn Phelps is ahead in the Wentworth count, but the final result has not yet been declared. 

Mr Turnbull sent a tweet supporting Mr Sharma and also sent private messages to him, but did not actively campaign while he was overseas.

“Doesn’t stack up for me … If I was in the cabinet – I’m not – I’d be scratching my head desperately,” Mr Joyce told 2GB radio.

“Now I’m on the backbench I can tell you the truth: it is a problem and there should have been a bit more thought put into this, I don’t think it’s the right move.”

-with AAP