Former Turnbull cabinet minister Darren Chester has slammed a $1 billion government slush fund over its lack of transparency after Fairfax Media revealed hundreds of millions of dollars were going to marginal electorates while safe seats missed out.

Mr Chester, who was controversially dumped from cabinet in a pre-Christmas reshuffle by Prime Minister Malcolm Turnbull, lashed the "Community Development Grants" program on Saturday over its opaque funding allocations.

"It's not the projects that are funded which are always the issue, it's the ones which miss out," he said.

"[The] lack of transparency on grant allocations is undermining public trust in our system of government."