Vodafone and O2, the mobile phone groups, could be forced to give up some of their most valuable bandwidth, as part of the government’s plan for all homes to have broadband internet access by 2012.

Under proposals published on Friday Ofcom, the industry regulator, O2, which is owned by Spain’s Telefónica, and Vodafone would be forced to relinquish part of the 900MHz spectrum which is suitable for transmitting much larger packets of data such as video and internet services.