Chief Minister Katy Gallagher does not use Assembly travel allowances for Labor Party events, choosing to pay her own way, but other members on all sides of the spectrum have dipped into the coffers for party conferences and meetings.

Last year Mr Rattenbury attended the Greens national conference in Brisbane in November, the three days costing $1768, and a meeting of the Greens national council in March, at $1547.

The guidelines are ill-defined, saying only ministers are entitled to the travel allowance if they are on official ministerial business.

Members closed ranks on the question yesterday, a spokesman for Liberal Leader Jeremy Hanson saying Mr Hanson had not used travel allowances for party events but he was "of the belief that the sort of travel [Mr Rattenbury] has taken is allowed".

Deputy Chief Minister Andrew Barr attended the 2011 national Labor conference in Sydney (where he played a part in Labor changing its platform on marriage equality), at a cost of $2066.

In 2009, then chief minister Jon Stanhope, and Labor member John Hargreaves attended Labor's national conference in Sydney on taxpayers' funds.

A spokesman for Ms Gallagher said she had paid for her own accommodation for the Labor Party conference in 2011 and had not claimed a travel allowance (although the airfare was paid because the visit coincided with an official engagement), but it was a matter for individual ministers to decide. The rules allowed this spending, based on NSW practice, she said.

Mr Rattenbury said he was transparent and meticulous about travel, and had sought advice from the Chief Minister's Directorate, which administers ministerial travel. The meetings allowed him to talk with colleagues from other jurisdictions about a range of policy and ministerial issues, he said.

Mr Rattenbury also visited Portland in the United States late last year to look at transport, housing and other initiatives, but he paid the airfare to the US himself, claiming only for a domestic airfare from Washington to Portland.

Overall, Mr Rattenbury's travel spending for the last six months of last year was the most modest of the ministers, at $5445.

The most expensive single trip was by Mr Barr, who spent $15,605 visiting Portland, San Francisco and Singapore on infrastructure, finance and tourism meetings over 11 days in November. His total travel bill for the six months was $21,705.

The five ministers combined spent $64,800 in the six months.

Guidelines for ordinary members are more clear than for ministers, thanks partly to Mr Rattenbury clarifying the rules when he was speaker in the last Assembly.

Ordinary members can claim travel allowance for Assembly business and for "studies and investigations". Mr Rattenbury took the view, in line with previous practice, that it should include party conferences.

Liberals Alistair Coe and Zed Seselja have also used the entitlement for party meetings.