Government ministers have called on frustrated Coalition MPs to air any concerns internally following an unnamed MP's reported threat to defect to the crossbench unless Prime Minister Malcolm Turnbull is replaced as leader by someone other than Foreign Minister Julie Bishop.

The disaffected MP's threat to quit the Coalition next month and imperil Mr Turnbull's working majority in the House of Representatives was reported by conservative News Corp commentator Andrew Bolt on Tuesday.

Ms Bishop, the deputy Liberal leader, said she was not aware of an MP holding these views but would be "very concerned" if it were the case.

"If they are thinking that way I'd hope they'd come and talk to me or talk to the Prime Minister about their concerns rather than talking to the media," she told Sky News.