The offices of Rupert Murdoch’s 21st Century Fox have been raided by officials from the European commission investigating a potential abuse of its dominant position in the broadcasting of major sports events.

Following reports that the competition regulator had gained access to the company’s offices in Hammersmith, west London, a spokesman for the commission confirmed that a series of “unannounced inspections” had taken place at the offices of unnamed companies in several EU countries.

A spokesman for Murdoch’s company confirmed: “Fox Networks Group (FNG) is cooperating fully with the EC inspection.” FNG is an operating unit of Fox, which distributes TV and cable channels and content around the world.

A commission spokesman said of the raids on Tuesday: “The European commission can confirm that on 10 April its officials carried out unannounced inspections in several member states at the premises of companies active in the distribution of media rights and related rights pertaining to various sports events and/or their broadcasting. Unannounced inspections are a preliminary step into suspected anticompetitive practices.”

The raids, during which documents and computer records were reportedly taken, had been prompted by concerns of the regulators in Brussels that Fox “may have violated EU antitrust rules that prohibit cartels and restrictive business practices”.

The entertainment giant is currently embroiled in a long-drawn-out takeover of Sky, during which it has fallen under intense scrutiny by regulators in London and Brussels. Fox has been trying to buy the 61% of Sky that it does not currently own.

In January the UK’s competition and markets authority provisionally found that if the deal went ahead as planned, it would give the Murdoch family too much control over news providers in the UK.

The regulator scrutinising the deal feared it could lead to the Murdoch family trust holding too much influence over public opinion and the political agenda.

Disney has offered to buy Sky News to help Murdoch seal his £11.7bn takeover of Sky by allaying fears he will control too much of the UK news media.

That deal would pave the way for Disney’s proposed $66bn (£47bn) takeover of most of 21st Century Fox, including all of Sky.

Sky had previously said it could close Sky News if Fox failed to gain regulatory clearance for its takeover bid.

Politicians including the former Labour leader Ed Miliband, the Liberal Democrat leader, Vince Cable, and the Conservative MP Ken Clarke have been outspoken in criticising the deal and calling for it to be blocked.

The UK’s Competition and Markets Authority aided the officials in their raid of the offices in west London, the commission said.

The commission spokesman added: “The fact that the commission carries out such inspections does not mean that the companies are guilty of anticompetitive behaviour nor does it prejudge the outcome of the investigation itself.

“The commission respects the rights of defence, in particular, the right of companies to be heard in antitrust proceedings.”

There is no legal deadline to complete inquiries into anticompetitive conduct.

While Fox’s takeover of Sky has fallen foul of the UK’s regulator, it was cleared unconditionally by Brussels last year. The commission found that there were no competition concerns in the proposed combination of Sky, the leading pay-TV operator in Austria, Germany, Ireland, Italy and the UK and 21st Century Fox, which owns one of the six major Hollywood film studios, as well as a TV channel.

Murdoch dropped his previous attempt to take control of Sky in 2010-11 through News Corp after the phone-hacking scandal at the News of the World hit the headlines.

As news of the raids emerged, shares in Fox fell more than 1%.