The Napthine government has foreshadowed tough new laws to prevent industrial strife hampering construction of the east-west link, setting the scene for a showdown with unions ahead of the 2014 state election.

With the state opposition opposed to the $6 billion to $8 billion tunnel, Treasurer Michael O'Brien warned there was no turning back, vowing that contracts to build the road would be locked in just weeks before the state election.

Although Victoria transferred its industrial relations powers to the Commonwealth during the Kennett years, it is believed the Napthine government will considering introducing major-projects legislation designed to limit the scope for industrial or legal action.

It follows revelations by Fairfax Media that, under the terms of the public private partnership, Victoria - ultimately the taxpayers - will bear the cost of any industrial action linked to government policy.