The construction arm of St Hilliers Property has placed itself in voluntary administration throwing into disarray building projects in the Illawarra, Shoalhaven, Coffs Harbour and Victoria.

The New South Wales Government announced just two months ago St Hilliers Construction as the successful tenderer to take over failed public housing projects in regional New South Wales.

Work on the sites is almost completed, but workers have not been paid.

Mick Lane from the construction union says the government needs to step in immediately.

"There's all sorts of dire consequences for a lot of sub-contractors if this is not fixed and fixed quickly", he said.

Mr Lane says he is trying to set up meetings but has already had distraught members on the phone.

"I've had a sub-contractor on the phone in tears this morning having ploughed hundreds of thousands of dollars in materials and labour (into the project)", he said.

Coffs Harbour Coalition MP Andrew Fraser says heads should roll and he has the Department of Housing in his sights.

"The Department of Housing ought to be hung out to dry," he said.

"I've got a call into the Minister.

"I'm waiting to hear back from him, but as far as I'm concerned we as a state government must make good these losses".

In Victoria, St Hilliers was working on a $350 million dollar expansion of the Ararat Prison.

A spokesman for the administrator says St Hilliers Ararat has gone into liquidation.