Virgin Media must open its underground pipes network to its rivals, BT has said.
It said it will be pressuring Ofcom to get it access to Virgin's network so it can upgrade its own infrastructure, according to the Times newspaper.
BT said it wants to sign up five million people to "superfast" broadband by spring 2011 and will open up its network of pipes to its competitors.
But Virgin Media chief executive Neil Berkett dismissed the idea as "a can of worms".
A spokesman for BT told the Times: "It is remarkable that those calling for open access from BT are not willing to provide it themselves. We call on others to follow BT's lead in offering to open its infrastructure and content to all on a fair basis. Competition is a two-way street."
The firm said it will be trying convince Ofcom over the coming months to force Virgin to open its cable infrastructure.