Political parties contesting next year's state election are being urged to reject campaign funding from property developers and the gambling, alcohol and tobacco industries if their current status as prohibited donors is overturned by the High Court.

The NSW Greens have written to parties registered for the March 2015 poll seeking the agreement in response to a High Court challenge to bans on donations from certain industries lodged by independent Newcastle lord mayor Jeff McCloy.

Cr McCloy, a property developer, is under investigation by the Independent Commission Against Corruption as part of its inquiry into alleged illegal fund-raising by the NSW Liberal Party, which resumes on Wednesday.

The ICAC is examining whether he and other banned donors, including mining magnate Nathan Tinkler and businessman Hilton Grugeon, "improperly sought to influence certain MPs by making donations during the 2011 state election campaign".

In documents filed with the High Court, Cr McCloy says he does not recall making a $10,000 donation to Newcastle MP Tim Owen.