Greens could block Melbourne freeway funds

A proposed $5.5 billion freeway through Melbourne's west could be in jeopardy with the Greens and the coalition set to block it in the upper house.

The West Gate Tunnel will be funded in part by giving tolling company Transurban a decade's extra tolls on existing toll roads, but that extension needs to go through parliament.

Greens leader Samantha Ratnam told ABC radio on Monday the party was considering joining with the opposition to block the toll extension, putting at risk the future of the road, which was not taken to the 2014 election.