Embarrassed MP Shane Jones was a potential future Labour Party leader, says a former party president.

Mike Williams was Labour Party president until two years ago, during the time Labour ministers - including Jones - misused their credit cards, as revealed in documents released today.

Jones admitted earlier today he had put pay-per-view adult movies on his taxpayer-funded credit card before paying it back from his own pocket.

Asked about Shane Jones's spending on adult movies, Mr Williams said he had not heard about it and "I need to think about that".

But the overall misuse of credit cards was common, he said.

"What I heard from a friend is they were all doing it - running up their members' debt, that sort of thing," Mr Williams said.

"It seems to me both sides of the political spectrum were running up personal debts and paying them back sort of immediately."

He had been president of the party until two years ago, but MPs' behaviour was "completely unknown territory to me", Mr Williams said.

Labour Party headquarters also told nzherald.co.nz today that it would not be commenting on the issue, as it was an issue for MPs.

Mr Williams said it would be up to public reaction whether any disciplinary action would result.

He was "out of touch" with the party, he said, but said Jones had been "one of six that could possibly be a leader into the future".

Last year, Jones became the target of jibes that he had ambitions for Labour's leadership, including from Prime Minister John Key, who in Parliament called Jones "the real leader of the Labour Party".