Tony Abbott has asked Malcolm Turnbull to appoint Brian Loughnane, the husband of his former chief of staff Peta Credlin, as Australia’s representative to the Vatican.

The former prime minister asked his successor for the favour after losing the Liberal party leadership in September, Guardian Australia has confirmed.

The request was initially reported in the Australian Financial Review.

Loughnane resigned as federal director of the Liberal party in October, after 12 years at the helm. He was replaced in December by party stalwart Tony Nutt.

Loughnane cited the leadership change as a good opportunity for him to step down.

“With the recent changes in the parliamentary leadership and the consequent need to review our planning for the next campaign, I believe now is an appropriate time for the party to appoint a new federal director to lead the organisation into the next campaign,” Loughnane said at the time.

Credlin became Abbott’s chief of staff in 2009, after he became opposition leader. She and Loughnane have been married since 2002.

Their relationship caused tension in the party, with the Liberal party’s former treasurer, Philip Higginson, issuing a scathing review of the pair in February last year.

In letters to the party leaked shortly after Abbott survived his first leadership challenge, Higginson criticised the nexus between Credlin and Loughnane as hurting the party.

“It immediately brings about the cessation of open communication to the federal director, contributes to wooden and unreliable communication, and a reluctance towards open and trusting lines of communication and, dare I say it, retribution,” he wrote. “In corporate Australia the chairman of the board would never allow his EA [executive assistant] to be wife of the managing director, or the managing director would never allow his EA to be the wife of the chairman.

“I am overwhelmed daily by the sheer vitriol and pent-up animosities and enmities that exist, and we are all personally affected by it and contributing to it the longer the conflict of interest exists.”

Abbott remained loyal to Credlin despite the criticism, dismissing concerns that she had wielded too much power.

“I stand by my staff,” Abbott told Channel Nine in February. “I certainly have full confidence in the party’s president, the party’s federal director. I’m aware of that particular storm in a teacup but the treasurer signed off on the party accounts. So I’m not quite sure what the fuss is over.”

The former QC John McCarthy is the current Australian ambassador to the Holy See, taking on the role from the former deputy prime minister Tim Fischer in 2012.