Media group News Corporation is lobbying US lawmakers to stop Congress overturning media ownership regulations that could force Rupert Murdoch to sell some US television stations.

Congress is contemplating rolling back several ownership rules but News Corp and rival Viacom are concerned about efforts to lower the national television ceiling.

The Federal Communications Commission last month voted to raise the cap - which prevented networks from owning stations with a combined audience of more than 35 per cent of the US audience - to 45 per cent.

News Corp, which owns Fox, and Viacom, owner of CBS, were both in breach of the 35 per cent limit and had lobbied Michael Powell, FCC chairman, to increase the cap. The FCC decision to relax ownership restrictions came under fire over fears the new ceiling would concentrate power in too few companies.

Mr Powell argued that the cap needed to be raised to allow network television to compete with cable and satellite television. However, House and Senate committees have now approved legislation that would reinstate the old cap.

Senator Byron L Dorgan has also introduced a congressional veto to return the cap to 35 per cent. The move could spell trouble for Viacom and News Corp, both of which could have to divest some of their television stations to comply with the new limit.

- (Financial Times Service)