The BBC's plans to offer all its TV and radio shows on-demand have been criticised by broadcasting watchdog Ofcom.

Aspects of the BBC's on-demand service, due to start later this year, could have a "negative effect" on rival services and limit investment elsewhere, says the regulator.

The BBC propose that viewers would be able to watch any BBC programme from the previous seven days via the internet, using its 'iPlayer', or through cable television services.

It added that while the BBC's plans would boost interest in other similar services, an outcome "would not be in the long-term public interest", and would impact on related markets such as DVD rentals and sales.

Ofcom has recommended that BBC reduces the proposed 13-week time limit in which viewers would be able to watch once downloaded.

The BBC Trust will now review Ofcom's findings, with an interim decision expected later this year.