Ofcom has invited applications for what would be the fifth high definition channel to broadcast on the Freeview terrestrial platform.

Its the third request made by the regulator for capacity in Multiplex B, currently occupied by BBC One HD, the BBC HD channel, ITV1 HD and Channel 4 HD and follows a report by licence holder BBC Free to View Limited that the MPEG-4 multiplex could take a further channel before the end of the year.

The new application is open to Public Sector Broadcasters, which include the Channel 3 licence holders (ITV, STV, UTV and Channel), Channel 5, Channel 4, and the Welsh Authority.

Ofcoms previous award had been due to be made to Channel 5, then owned by RTL, but the DTT allocation committee withdrew the offer in February 2010, allowing BBC One HD to launch the following November.

The closing date for applications is October 17, 2011.