The government has said it will introduce stronger rules to prevent foreign broadcasters from invading British television screens with cheap imports following the relaxation of ownership rules.

Tessa Jowell, the culture secretary, also insisted that the "digital revolution" is still on track, saying that the target of switching off the existing analogue signal by 2010 remains achievable.

Broadcasters such as the BBC and ITV could face fines if they fail to meet quotas for buying in programmes from independent TV producers.