It will cost billions to fulfill the coalition government's vision of getting fast broadband to every part of Britain, BT has said.

Steve Robertson, chief executive of BT Openreach, told BBC Radio 5 Live that the goal cannot be achieved without public funds of around £2bn.

The costs of delivering basic broadband to rural areas may also rise, experts say.

The government says industry must find ways to solve the problems.

It has pledged to make the UK the fastest broadband nation in Europe by 2015 and provide a minimum 2Mbps to every home.

But, other than £175m set aside from the Digital Switchover project, there is little new money available to fund these rollouts.

Culture minister Jeremy Hunt told BBC News that the costs "had been scoped out" and he was confident "we should be able to deliver on our commitment."

"Obviously we are looking for solutions that allow extensions to superfast [broadband]. It would be a short-term fix if 2 megabits was the limit," he told BBC News.

He said the levy on the BBC licence fee used to fund digital switchover could be extended if necessary.