News Corp is expecting to formally notify the European commission this week of its intention to bid for BSkyB.

The move will kickstart a regulatory process that could result in the media conglomerate's offer to buy the 61% of Sky it does not already own being blocked by the business secretary, Vince Cable.

News Corp offered to pay 700p a share for the Sky stake in June, but the board of the pay-TV group wants it to increase its offer. Both parties have agreed to defer negotiations while News Corp seeks regulatory clearance. The commission has the power to investigate the deal on competition grounds because of the size of the transaction and the fact that both companies have a pan-European presence.

Cable can also intervene on "media plurality" grounds. He is expected to decide within a fortnight whether to refer the deal to media regulator Ofcom. The decision is politically explosive because of the close links between the News Corp chairman, Rupert Murdoch, and senior Conservatives, including the prime minister.

The business secretary is under intense pressure to intervene in the deal from some members of his own party.

A powerful alliance of media groups, including Guardian Media Group – which publishes the Guardian – Channel 4 and the BBC, have also written to him asking for the deal to be investigated.

They argue that the combined power of News Corp's UK newspapers, which include the Sun and the Times, and Sky, which this year made record profits of just over £1bn, would give it unprecedented market dominance.

If Cable does intervene he will ask for initial advice from Ofcom on whether the deal should be subjected to more detailed scrutiny. Ofcom is likely to take around two months to come back to him.

If it says the takeover warrants further investigation, Cable can ask the Competition Commission to carry out a further assessment of the impact of the deal on the media market. That is likely to last until early next summer.

Under that scenario, Cable would make a final decision based on the Competition Commission's findings and the Ofcom advice. He can wave the deal through at any stage. It is for the European Commission to rule on whether there are grounds to block the takeover on competition grounds. The OFT can ask the commission to allow it to take charge of that investigation but is not expected to do so.

The commission will conduct an initial assessment lasting 25 days before deciding whether to carry out a more detailed probe. It is concerned about the power Sky wields over the football rights markets in the European countries in which it operates, according to a source close to it.

The source added that the commission was unlikely to trigger a full competition investigation, however, because it did not believe there were legal grounds to block the proposed takeover.