Barnaby Joyce spent more than $10,000 on family reunion travel while having an affair with his former staffer, raising more questions about taxpayer funds being used to support the double life led by the Deputy Prime Minister.

Claims made under parliamentary entitlements from January to September last year show that more than $10,000 was spent on family travel, which is allowed so that MPs can “balance their work and family responsibilities”.

The rules are also designed to help MPs “reconcile the need for them to be away from home for long periods with their family obligations”.

More than half of the family travel expenditure was reported from July to September, while Mr Joyce’s mistress Vikki Campion was already pregnant with his fifth child.

Most of the travel reported is for airfares between Mr Joyce’s home base of Tamworth and Canberra or Sydney.

From July to September, three family travellers were nominated, taking a total of nine separate trips at a total cost of $5820.

One of the trips was for Mrs Joyce to attend the Mid Winter Ball in Canberra on June 14, which was reportedly orchestrated to end the damaging rumours about the affair. The return flights from Canberra to Tamworth for the event were reported at $1274.

Figures for the period September to December, when Mr Joyce told Parliament that his marriage was over, have not yet been made public by the Parliamentary Expenses Authority.

Mr Joyce’s office yesterday refused to answer questions about the travel allowance, which was used on several occasions for his now-estranged wife Natalie Joyce.

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The revelation will heap further pressure on the Nationals leader who has come under fire for the long-running affair with his 33-year-old former media adviser — who is now his partner.

Mr Joyce this morning denied breaching the ministerial code of conduct, saying the Ms Campion wasn’t his partner when she worked for him or his cabinet colleague Matt Canavan.

The deputy prime minister and Nationals leader also publicly apologised to his wife Natalie and four daughters, Ms Campion and supporters and constituents for the distress the public airing of the affair has caused.

Mr Joyce denied allegations in media reports he sexually harassed a woman in 2011 and said he reserved his legal rights on the matter.

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Labor targeted the Federal Government over his relationship in question time yesterday, asking who approved the appointment of Ms Campion to high-paying roles in the office of other Nationals MPs.

Prime Minister Malcolm Turnbull said the Nationals were allocated a set number of staff positions based on their numbers within the coalition, but how they were allocated was up to them.

“The distribution of those staff members between Nationals offices is a matter for the National party,” he said. “At no time did the Nationals fill all vacant staffing positions.”

Mr Turnbull also insisted that he had not been made aware of the staffing arrangements for Ms Campion, who was transferred from Mr Joyce’s office to that of Nationals senator Matt Canavan, then to the office of the party’s chief whip, Damian Drum.

Labor also questioned Mr Joyce over his portfolio responsibilities, with frontbencher Anthony Albanese saying the newly minted infrastructure minister was “simply not up to the job”.

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Questions have also been raised about whether Ms Campion was officially Mr Joyce’s partner, with the statement of ministerial standards forbidding MPs from employing their partner without the approval of the prime minister.

Senior coalition figures have expressed concern that further damaging revelations could yet emerge about Mr Joyce’s conduct, with some believing his position as Deputy Prime Minister is untenable. Mr Turnbull answered “yes” when asked if he had full confidence in Mr Joyce, who will be acting PM next week.

Indigenous Affairs Minister Nigel Scullion said Mr Joyce had “100 per cent” support of the Nationals party room and he defended Ms Campion’s employment arrangements.

Meanwhile, it was revealed Mr Joyce and Ms Campion not only lived rent-free at a home owned by Greg Maguire, a millionaire from his electorate, but that they have also holidayed at no cost at the businessman’s $4000-a-week beachfront house in Wooli on the NSW north coast.

- With AAP