Barnaby Joyce would have been personally responsible for approving highly-paid jobs handed to his now-pregnant former staffer Vikki Campion, the Turnbull government has admitted.

The concession came during a feisty Question Time as Labor pursued Mr Joyce over who approved two newly-created jobs for Ms Campion within the offices of Matt Canavan and Damian Drum.

Asked which Minister would have approved the positions, Scott Morrison confirmed it was Mr Joyce, though he said he did not “go along with the idea” that they were additional positions.

“These are addressed by the Leader of the National Party,” said Mr Morrison, representing the Special Minister of State.

Prime Minister Malcolm Turnbull also distanced himself from the arrangement, saying the jobs were a matter for the National Party.

“I’m advised that the Nationals are provided with a number of personal staff positions as a share of the government’s overall staffing pool,” he said.

“The distribution of those staff members between Nationals’ offices is a matter for the National Party.

“I’m further advised that at no time did the Nationals fill all vacant staffing positions.”

He noted Mr Joyce had stated he “had not discussed Ms Campion’s employment with me or my office” but his office had an “administrative role in informing the Department of Finance of changes”.

It was also confirmed Mr Joyce will serve as Acting PM when Mr Turnbull heads to the United States next week.

Asked by Bill Shorten if Mr Joyce would serve as Acting PM and whether he retained the Prime Minister’s full confidence, Mr Turnbull replied: “Yes to both questions.”

Labor chose not to directly ask Mr Joyce whether he had broken ministerial standards by appointing Ms Campion to government jobs while it appeared they were in a relationship.

Section 2.23 of the Ministerial Standards states: “Ministers’ close relatives and partners are not to be appointed to positions in their ministerial or electorate offices, and must not be employed in the offices of other members of the Executive Government without the Prime Minister’s express approval.

“A close relative or partner of a Minister is not to be appointed to any position in an agency in the Minister’s own portfolio if the appointment is subject to the agreement of the Minister or Cabinet.”

The Prime Minister’s office had argued the standards were not breached because Ms Campion was not Mr Joyce’s partner at the time.

His office said Mr Turnbull was not aware of the relationship at the time, contradicting reports the PM was told of the affair and instructed that Ms Campion be removed from Mr Joyce’s staff.

Ms Campion reportedly held the second job in Mr Drum’s office, worth about $190,000, until December last year.

Labor MP Wayne Swan described suggestions from the PM’s office that Mr Joyce and Ms Campion were not in a relationship “breathtaking”.

“They’re claiming that the woman that the Deputy Prime Minister has a relationship with is not his partner, and therefore the code of conduct doesn’t apply,” he told Sky News.

“Tell that to any Centrelink recipient who’s having this argument about co-habitation.”

Labor sought to gauge whether Mr Joyce was being distracted by his personal turmoil by four times asking specific questions about infrastructure funding in Tasmania, Victoria, South Australia and the Northern Territory.

He took on the portfolio late last year in a ministerial reshuffle.

Labor’s infrastructure spokesman Anthony Albanese said Mr Joyce’s answers, including one in which he “argued inland rail would benefit Tasmania”, meant the he “was simply not up to the job”.

But Mr Joyce hit back, suggesting that Mr Albanese was using Question Time to “show his wares” in a bid to claim the Labor leadership from Bill Shorten.

“Good luck, old mate,” he told Mr Albanese.