Rupert Murdoch will have to increase his bid for BSkyB by as much as 20% if he is given the go-ahead by regulators, analysts warned last week, after the broadcaster unveiled another set of stellar results.

Sky announced that profits had soared 26% to £520m (€606m) in the six months to 31 December as it reached 10 million customers. The whole company is now valued at more than £13bn.

Revenues were up 15% at £3.2bn, which should strengthen the independent board's hand in its negotiations with Murdoch's News Corporation.

NewsCorp owns 39.1% of Sky and approached in June with a 700p per share offer to buy the rest of the company. The board rejected the approach but said it would accept a price above 800p.

Both sides are waiting for regulatory approval from British culture minister Jeremy Hunt, who is scrutinising the deal on plurality grounds.

Steve Liechti, an analyst at Investec, expects the deal to be done by the autumn but believes that NewsCorp will have to pay 840p per share.

Paul Richards, of Numis, said he did not believe the deal raised competition or plurality issues, adding that the deal could cost NewsCorp as much as 850p per share.