Federal Opposition Leader Tony Abbott has put himself on a collision course with his Victorian allies in the Napthine government, declaring he would not support its top priority public transport project, the Melbourne Metro rail tunnel.

Mr Abbott said the federal government had no history of funding urban rail projects, but a long history of funding roads.

He said this was why the federal Coalition had already committed $1.5 billion to the east-west link, a proposed 18-kilometre road through Melbourne's north.

"We spoke to Infrastructure Australia and their advice was that the most pressing road priority in Melbourne was the east-west link," Mr Abbott told reporters in Frankston on Thursday.

"Now the Commonwealth government has a long history of funding roads. We have no history of funding urban rail and I think it's important that we stick to our knitting, and the Commonwealth's knitting when it comes to funding infrastructure is roads."