Accusations of economic untruth are being flung from all sides of the political arena today, with Federal Budgetary Office and federal Treasury policy costings called into question.

The Government is standing by its combination of figures from both departments, which reportedly show a $10 billion hole in budgetary savings claims from the Opposition.

Senior public servants have today taken the unusual step of rebuking last night's claims from Prime Minister Kevin Rudd, Treasurer Chris Bowen and Finance Minister Penny Wong, who said the Opposition's plans would save only $21 billion, rather than the $31 it purported.

A joint statement from the PBO and Treasury has called The Government's interpretation of figures “inappropriate”, saying “different costings assumptions, such as the start date of a policy, take-up assumptions, indexation and the coverage that applies, will inevitably generate different financial outcomes.”

The Opposition has defended its costings, and attacked The Government's. Opposition Leader Tony Abbott said in a radio interview: “This is a PM who gets his own costings wrong, massively, and now he's getting our costings wrong... if Kevin Rudd is talking about costings while he's moving his lips, you know he's not telling the truth... what we've promised to spend so far is in the order of $20 billion and what we've promised to save is in the order of $30 billion.”

Finance Minister Penny Wong responded in a separate interview, saying “Mr Abbott, if your policies are all costed, why won't you put them out?”

“...Joe Hockey keeps lying on national television saying Labor hasn't costed its policies. We have. We've lodged 46 policies under the Charter of Budget Honesty. The Coalition has lodged none.”

Shadow Treasurer Joe Hockey says the Coalition will release its costings next week.