The British offices of the Murdoch entertainment empire 21st Century Fox have been raided by investigators from the European Commission, The Daily Telegraph can reveal.

It is understood that competition watchdogs gained access to the company’s offices in Hammersmith, west London, early on Tuesday to seize documents and computer records.

The full details of the confidential investigation, which is believed to be in its early stages, have yet to be revealed. The building is home to Fox Networks, the company’s channels business.

The European Commission confirmed it is investigating media companies across the EU over a suspected cartel in sports rights distribution and broadcasting.

Investigators are able to take copies of documents and computer records, and ask for explanations from executives.

Sources at the 10 Hammersmith Grove development, which is shared with the tobacco company Philip Morris among others, said Commission officials were attempting to keep a low profile and that staff had been warned to keep details of the raid secret. It is understood that investigators are expected to remain on site through Wednesday and possibly into Thursday.

The EU's competition enforcement is overseen by Commissioner Margrethe Vestager

The raid comes at an extremely sensitive time for Fox as it seeks a remedies agreement with British watchdogs at the Competition and Markets Authority (CMA) to secure its heavily delayed takeover of Sky.

The CMA is considering an offer from the Murdoch family to spin off Sky News into a separate company or sell it to Disney to assuage concerns that full control of Sky will give them too much sway over the British media. The deal has already been approved by the European Commission.

Following an investigation into the impact of full Murdoch control on the public interest in media plurality in the UK, the CMA is due to make recommendations to the Culture Secretary Matt Hancock by next month on whether to allow or block the deal.

News of a competition investigation by the European Commission will be viewed as a boost to the US cable giant Comcast, which is seeking to disrupt Fox’s takeover of Sky with its own rival £22bn bid.

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The stakes are very high. Fox has also struck a $66bn deal to sell most of its assets, including Sky, on to Disney. The Murdoch family plans to sell up to focus on US news and sports broadcasting as Hollywood studios race to gain heft to make themselves more able to withstand the expected onslaught on entertainment by Silicon Valley tech giants.

Disney’s offer to buy Sky News prior to that bigger transaction was interpreted by analysts as a sign of chairman Bob Iger’s determination to gain control of Britain’s dominant pay-TV operator.

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Any new obstacle in a Fox bid for Sky that is due to have run for at least 18 months by the time Mr Hancock makes his decision could also be seen as an obstacle to the Disney takeover. Fox already faces a potential bidding war with Comcast, which has made an approach for Sky at a 16pc premium to the current Murdoch offer.

A Fox spokesman said: "Fox Networks Group (FNG) is cooperating fully with the EC inspection.”

A Commission spokesman said: “Unannounced inspections are a preliminary step into suspected anticompetitive practices. The fact that the Commission carries out such inspections does not mean that the companies are guilty of anti-competitive behaviour nor does it prejudge the outcome of the investigation itself. ”