The leaking of classified defence documents has been described as a matter of national security by Treasurer Scott Morrison amid ongoing tensions within the Coalition.

Key points: Treasurer Scott Morrison says people should not be playing politics over matters of national security

Treasurer Scott Morrison says people should not be playing politics over matters of national security Senator Eric Abetz suggests the leak may not have come from a politician

Senator Eric Abetz suggests the leak may not have come from a politician Coalition backbencher says any hopes Tony Abbott had of becoming PM again "died with [Wednesday's] Australian newspaper"

A report published by News Corp this week referenced "several sections of the draft white paper" produced under former prime minister Tony Abbott and his defence minister, Kevin Andrews.

At the heart of the revelation was the timing of when the Government planned to have the next fleet of submarines in action.

The leaked documents allegedly reveal that Prime Minister Malcolm Turnbull plans to deliver the next fleet of submarines in the 2030s, almost a decade after Mr Abbott planned to.

Rather than drawing focus away from the leak, members of cabinet are publicly criticising the "culprit" and calling for the Australian Federal Police (AFP) to identify the mystery leaker.

Mr Morrison told the ABC it was being treating as a breach of national security.

"It is a very serious matter," he said.

"I think the Prime Minister has done exactly the right thing in terms of the integrity of that process. And if someone has been found to have violated that, well that's very disappointing [and] national security is not something people should play politics over."

Foreign Minister Julie Bishop also weighed in, stating that leaking is a criminal offence.

Abetz backs Abbott but ministers suspect former PM

Mr Abbott has denied leaking the documents and was backed by Liberal Senator Eric Abetz on Thursday morning.

Senator Abetz told the ABC there was a question to whether it was a politician at all.

"I think it is a big jump to suggest it was a parliamentarian," he said.

"There is an investigation, so let's see what that produces, but leaks should be condemned whether by Parliamentarians or indeed by officials."

But there is ongoing tension within the Coalition, with sources telling the ABC it appeared Mr Abbott had broken his promise not to undermine his successor.

"Abbott's still in the angry phase — people are starting to get annoyed," one minister said.

"It's scrappy, it's just not useful," said another minister, but tried to differentiate the situation to what was experienced during the Rudd-Gillard years.

"The noise is coming from quite a small group; Rudd had a bloc of support."

A Coalition backbencher described it as "the last death roll of a past leader".

"If Tony Abbott had any thoughts of a return to the prime ministership, they died with [Wednesday's] Australian newspaper," the backbencher said.

The AFP said it will investigate according to its normal protocols.