VICTORIAN police have charged a man who has allegedly threatened to detonate numerous "bushfire bombs" across the state.

Paul Hill, 75, was arrested on Tuesday evening at his rural property near Apollo Bay in the state's south-west, after authorities became concerned with his social media posts.

He has been charged with two counts of blackmail, one count of stalking and one count of making an explosive substance.

Police are also investigating alleged threats from Mr Hill to government and non-government organisations and individuals, including Premier Daniel Andrews, health workers, ASIO officers, journalists, academics and stock markets.

Arson and Explosives Squad detectives spent Wednesday scouring bushland near his property looking for any hidden devices.

Mr Hill appeared briefly in Geelong Magistrates Court on Wednesday and was refused bail.

- APN NEWSDESK.