German-based media firm RTL is considering a serious bid for broadcaster ITV, with reports suggesting it will make an announcement "within days".

RTL chief executive Gerhard Zeiler said earlier in the week that such reports were "pure speculation", but did not confirm what its future plans were.

It is known that RTL, which is Europe's largest television, radio and production group, has wanted to increase its share in the UK market for some time. The company operates 36 television channels and 33 radio stations in 11 countries across Europe and as well as Five, owns FremantleMedia and TalkbackThames in the UK.

Parent company Bertelsmann made a bid to buy former ITV company Carlton some years ago, though the deal collapsed due to financing issues.

It has not been confirmed whether the company would raise money to pay for ITV itself or partner with a private equity firm. Bertelsmann has debts of £6 billion, which it could reduce by selling BMG Music Publishing.

The firm would also have to consider its ownership of Five, which could prevent a deal going ahead. The combined broadcasters' viewing share is 61.72%, and the Competitions Commission may take a dim view on the impact this may have on the commercial market. Though city sources say a sale of Five is unlikely now Sky has ruled itself out of a bid.

Separately, media group WPP's chief executive Sir Martin Sorrell has said former Channel 4 boss Michael Jackson is his preferred candidate for the ITV chief executive role. Speaking at a conference in Barcelona, he called him "a fantastic choice and a much needed choice." Jackson is likely to be appointed chief executive of ITV if NTL's bid for the broadcaster is successful.