Former Labor leader Mark Latham has launched a vitriolic attack on Kevin Rudd, accusing him of being the source of the latest leak to hit the Gillard Government.

Mr Latham called the former prime minister a "snake" and said he should "be a man" and own up to the leak, which claimed Prime Minister Julia Gillard was opposed to the Government's parental leave scheme and questioned the aged pension rise.

"It's the coward's way to get on the blower with Laurie Oakes and say, 'I'll tell you this but you're not allowed to identify me'. It's the snake's way," he said.

"I challenge Kevin Rudd to be a man, to be honest, to have some honour, and actually if he feels this strongly about it, put his name to his words."

The firebrand former opposition leader told Sky News he was sure Mr Rudd leaked the information to Channel Nine reporter Laurie Oakes.

"When you're lying in bed at night and hear the pitter-patter sound on the roof you don't actually have to see the drops to know that it's raining," he said.

"So too, you don't need to have a wire tap on the conversation between Kevin Rudd and Laurie Oakes to know it was Kevin Rudd.

"It too is one of the laws of nature, that Kevin is a serial leaker."

He said Ms Gillard's decision to leave Mr Rudd on the backbench would have contributed to the leak.

"I think he was insulted when having lost the prime ministership and wanting to go onto the frontbench he wasn't accommodated," Mr Latham said.

"He was really quite humiliated by being left on the backbench by Julia Gillard."

Mr Rudd's spokesman has issued a one-line statement in response:"Mr Rudd has not responded to the substance of anything Mr Latham has said over the past five years. He does not intend to start now."

Previously, Mr Rudd issued a statement saying he never comments on private Cabinet discussions.

Ms Gillard has said she thinks Mr Rudd is "honourable" and is welcome on her frontbench if Labor wins the upcoming election.