Claire Enders, the founder of Enders Analysis, has written to the UK Business Secretary, Vince Cable, asking him to block Rupert Murdoch's full takeover of pay TV group BSkyB.
While Murdoch already owns 39.1 per cent of Sky, Enders said that allowing him to acquire the remaining 60.9 per cent of the pay TV operator would represent a "Berlusconi moment" for the UK.
In a 20-page submission to Cable last month, Enders, a media commentator and analyst, argued that letting the deal happen would see media plurality in Britain falling to an "unacceptably low level". The full text of the letter was published on the Beehive City media industry website on Monday.
Enders noted that the proposed deal demands "urgent attention" from the government, as the strength of Murdoch owned companies in their relative industries is growing quite rapidly compared to their peers.
She expressed concern that the leading positions of Sky in the UK TV market and of News Corp in the newspaper market will further strengthen by 2014.
Enders suggested that Cable could block the takeover on media plurality grounds, under the 2003 Communications Act.
It is understood that Cable has several weeks to decide over the matter and is likely to take advice from Ofcom.