Business secretary Vince Cable took a "short introductory phone call" from News Corp executive James Murdoch on 10 June, the government confirmed last night. The conversation took place on the day News Corp made a bid for BSkyB.

Cable will decide within weeks whether to approve News Corp's offer to buy the 61% of the pay-TV company it does not already own. An unprecedented alliance of media companies, including the Guardian's owner, Guardian Media Group, has written to Cable urging him to block the deal on public interest grounds.

What was said during the call has not been disclosed, but a source close to News Corp confirmed that Murdoch had phoned Cable on the day the BSkyB offer was made, out of courtesy. The fact that the call took place was revealed in a written answer to a parliamentary question tabled by Labour MP Michael Dugher.

Business minister Ed Davey wrote in reply: "[Vince Cable] had a short introductory phone call with James Murdoch of News Corporation on 15 June 2010." The answer was posted on the parliamentary website late yesterday.

Other media groups, including the BBC, Daily Mail owner Associated Newspapers, and Telegraph Media Group, which publishes the Daily Telegraph, have signed the letter to Cable.

They argue that News Corp's proposed purchase of Sky would give the company unprecedented market power and would have "serious and far-reaching consequences for media plurality".

Cable has the power to block the deal on public interest grounds.

A number of questions asking for details of any meeting between members of the government and News Corp, including the company's chairman and chief executive Rupert Murdoch, have been tabled by MPs.

It was reported yesterday that Downing Street is reluctant to answer such questions because they will draw attention to what might be construed as the close ties between the government and Murdoch's media empire. Rupert Murdoch visited the prime minister at No 10 shortly after the formation of the coalition government.

The Commons authorities have rejected another question Dugher tried to put down, asking for details of meeting between News Corp executives and deputy prime minister Nick Clegg.

In his written answer, Davey also disclosed that culture Minister Ed Vaizey met Rebekah Brooks, chief executive of News Corp's UK newspaper subsidiary, News International, on 12 July. NI's titles include the Times, the Sun and the News of the World.

An earlier answer in response to Labour MP Luciana Berger reveals that culture secretary Jeremy Hunt met James Murdoch on 28 June and BSkyB chief executive Jeremy Darroch on 21 July.