At least 28 major defence projects are a cumulative century behind schedule and 18 are over budget, the government has revealed.

The projects include Hunter class frigates, battlefield airlifters, patrol boats, the battlefield command system, a series of satellite communications projects and the P-8A Poseidon aircraft.

At least $6.5 billion of project variations outside of the budget have also been identified. 

Treasurer Jim Chalmers and Defence Minister Richard Marles will on Monday reveal budget pressures facing the defence department.

The government says a large proportion of the overspend is because of exchange rates and indexation, but also blamed the former coalition government for “chaotic administration”.

“The former Coalition Government’s investment in defence saw key defence projects blow out in both cost and time, money being flushed down the toilet,” Mr Marles said.

Mr Marles said the government would deliver on its defence commitments by establishing an independent office to hold projects accountable.

Monthly reports on projects of concern and interest will also be handed to the defence minister directly. 

The government will also allocate extra resources to troubled projects to help get them off the ground.

“It’s not as though we can go onto the battlefield and overwhelm our adversary by running up to them and waving a copy of the budget papers in their face,” Mr Marles said. 

He said prudential budget management was needed to get nuclear submarines in the water as soon as possible. 

But the government is pledging to maintain its commitment to spending at least 2 per cent of GDP on defence. 

Expenditure is set to increase to more than $80 billion by 2032.

By Dominic Giannini in Canberra

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