Health Minister Peter Dutton has defended his embattled colleague Fiona Nash, describing her as "effective" and "decent" and accusing state Labor ministers of leaking against her.

Senator Nash, the Assistant Minister for Health, is under pressure to resign from the ministry over her handling of the interests of her former chief of staff, Alastair Furnival.

Deputy Leader of The Nationals Senator Fiona Nash at question time on Wednesday. Credit:Alex Ellinghausen

Mr Furnival resigned on Friday, denying he had acted improperly but citing a "smear campaign" over his role in taking down a healthy food rating website, which he said was a distraction from the government's work in health.

Fairfax Media revealed on Tuesday that Mr Furnival also played a key role in stripping Australia's peak drug and alcohol body of its funding.