Shorten questions timing of task force

Federal Labor believes the government has timed the announcement of a joint federal and Victorian police task force to fight union corruption to coincide with the state election.

Prime Minister Tony Abbott and Liberal Premier Denis Napthine revealed the task force in Melbourne on Friday.

Evidence given to the national royal commission into trade union corruption prompted the measure.

Mr Abbott wants the task force to have bipartisan support given Opposition Leader Bill Shorten called for one earlier this year.

Mr Shorten responded: "Imitation is the best form of flattery".

"This copycat PM really just has to explain why he has waited nine months to make this announcement," he said.

"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."

Victoria goes to the polls on November 29.