Opposition Leader Bill Shorten’s office has confirmed he spent roughly $1300 of taxpayers’ money on a day he attended a party fundraiser but says he was also doing portfolio work.

Mr Shorten’s office said he flew from Melbourne to Sydney in October 2013 for the Maritime Union of Australia’s national council meeting in his role as Labor’s employment spokesman.

A spokesman for Mr Shorten said he attended a fundraiser later that day linked to the party’s leadership contest between him and fellow frontbencher Anthony Albanese.

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The spokesman said Mr Shorten was invited to the union meeting weeks before the fundraiser and the entitlements claim, for flights and car costs, was well within the rules.

“On October 9, Mr Shorten travelled to Sydney to speak at the MUA National Council, which he was invited to address nearly a month earlier,” Mr Shorten’s spokesman said in a statement.

“After travelling to Sydney for this work commitment, he remained for a fundraiser with Anthony Albanese.

“This is a common occurrence amongst all politicians, including Mr Abbott.

“I can confirm no luxury helicopters were hired for this trip.”

However, the day after the event Labor frontbencher Chris Bowen told the ABC’s 7.30 host Leigh Sales that Mr Shorten had not used his entitlements to pay for the trip.

She asked: “What’s the taxpayers’ share of the bill for the Labor leadership campaign, the candidates travel, the events and so on?”

“Well, the candidates travel is zero. They do not claim their public – their MPs entitlements to pay for their travel,” Mr Bowen said at the time.

“They had a fundraiser, a joint fundraiser last night in Sydney which made a contribution to their publications. We thought it was important that be the case.

“They’re running as candidates for the leadership not as shadow ministers, so they didn’t use their entitlements, as they would have been – as they would have under other circumstances.”

Mr Bowen on Monday evening defended his remarks in 2013.

“The two candidates for the leadership did not claim travel related to their campaign, as reflected in my comments at the time,” he said.

“Bill Shorten had previously arranged shadow ministerial business that would have been covered.”

Agriculture Minister Barnaby Joyce has seized on the news.

“I just think it looks poor if everybody sort of runs out and jumps on a person and then, because the next thing you know they’re in trouble as well and we saw that today with Mr Shorten,” he said.