Victorian trade unions say they have no tolerance for corruption but claim the announcement of a police probe into the building industry is a red-hot political stunt.

Prime Minister Tony Abbott says a joint federal and state police taskforce was developed after evidence of violence and criminal activity by union officials and associates was aired during the unions royal commission.

"It's very important under these circumstances that this kind of criminal activity be fully investigated and tackled by the people who are best-placed to deal with this and obviously that's the police," he told reporters.

He said the joint police taskforce established with Premier Denis Napthine would "firmly, decisively and swiftly" deal with widespread corruption, violence and organised crime connections inside the construction industry.

Mr Abbott said police could also better protect witnesses, as witness intimidation had emerged as a significant issue.

"Part of the work of this taskforce will be ensuring that witnesses are protected, because if we are going to get to the bottom of serious crime, if we are going to get to the bottom of what sometimes looks like a conspiracy between the CFMEU and organised crime, we have to be able to protect witnesses," he said.

Dr Napthine said Friday's announcement was made in the interests of law, not to get his government re-elected on November 29.

"This is an announcement about stamping out corruption, stamping out illegal behaviour in the building and construction industry," he said.

But ACTU assistant secretary Tim Lyons said it was a "red-hot political stunt" to divert attention from recent federal policies which had reflected badly on the Victorian government.

"Any time you see politicians, as you did today, announcing what the police are going to do it's deeply political," Mr Lyons told reporters.

CFMEU national construction secretary Dave Noonan said the measure had the hallmarks of a political stunt, but the union would co-operate with police.

"If the police have got something they want to discuss with us we will be frank, we will be co-operative and we've got no tolerance or time for people acting corruptly in the industry," he told ABC radio.

Mr Abbott called for bipartisan support of the measure but federal Labor, who called for the same taskforce nine months ago, has questioned the government's agenda.

Opposition Leader Bill Shorten said "imitation is the best form of flattery".

"I suspect ... the timing of it is more to do with Victorian electoral politics, based on the chaos he has created for the Napthine government," Mr Shorten said.

Victorian Opposition Leader Daniel Andrews said he didn't tell police what to do but welcomed the taskforce which he had also called for since February.

"Any Victorian, any Australian who is doing the wrong thing, the police should be after them and they should feel the full force of the law," he said.

About 30 federal and Victorian police will join forces in the taskforce, a model the government expects to mirror in other states.