Globe-trotting ministers should leave their spouses behind or pay for the trip themselves as part of efforts to trim the Government's travel bill, Prime Minister John Key said yesterday.

Mr Key has come under fire since Budget papers showed National ministers' travel costs for their first three months in government came to $739,000 - more than double the $336,000 of Labour ministers over the same period the year before.

Labour leader Phil Goff has accused National of hypocrisy after demanding other government departments trim their costs, saying it showed a "willingness of ministers to spend up large on themselves" despite the tough economic times.

Mr Key said it was "a cheap shot" from Mr Goff, who as trade, foreign affairs and defence minister had spent $2 million on travel from 2000 to 2008.

Labour ministers had often travelled with their spouse - allowed if the Cabinet approves of the travel.

However, Mr Key has told his colleagues that things are different because of the tough economic times.

"I made it clear to my ministers I didn't expect them to take their spouse and, to the best of my knowledge, they haven't. If they have, they've paid for it."

He said there were possibly some exceptions on trips to Australia.

"In every other instance, I've told them if they want to take their partner, they can do it, but they pay for it. When I went to China, it's well documented I took Bronagh and I paid for her."

He said that as a general rule, ministers also took only one staff member with them, and he personally travelled with an adviser and a press secretary.

"When I see the delegations that come to New Zealand, I've got to say it's pretty modest."

The same Treasury paper also shows National's ministerial travel bill for its first three months was still much smaller than Labour's in its last three months - Labour ministers racked up $1.09 million in travel costs from July to October last year, just before the November election.

Much of National's bill was for travel by the PM, Foreign Minister Murray McCully and Trade Minister Tim Groser.

"Of course, we've got to be careful with spending taxpayers' dollars," Mr Key said, "and I don't want to see ministers travelling around the world for no particular reason. But a lot of that cost was establishing those relationships, it was travel to Australia, and establishing relationships where there's a big economic advantage to New Zealand."

It included dealing with India, Korea, China and Malaysia over free-trade relationships.

In the paper to Finance Minister Bill English, the Treasury has recommended a formal review of Ministerial Services - including the standard practice for travel and expenses - to ensure its spending is cost effective.