A regional infrastructure grants program administered by the Deputy Prime Minister awarded 94 per cent of its grants to electorates held or targeted by the Coalition in the months leading up to the federal election.

A day after the Nationals' Bridget McKenzie resigned as agriculture minister over the $100 million sports grants saga, Labor infrastructure spokeswoman Catherine King has asked the Auditor-General to "take a thorough look" at the Building Better Regions Fund infrastructure grants program administered by Michael McCormack.

Deputy Prime Minister Michael McCormack (right), seen with Prime Minister Scott Morrison, said more Coalition seats received grants because "we hold more regional seats". Credit:AAP

Analysis by Nine News, The Sydney Morning Herald and The Age reveals 156 of the 166 infrastructure grants announced two months before the election went to Coalition-held seats, or electorates the Coalition was targeting.

"This appears to be another Morrison government rort," Ms King said.