Reports are circulating of potential suitors for a takeover of Yahoo, lifting the troubled web firm's shares and heralding major implications for the market. However, Yahoo will offer no confirmation on any of the speculation arising in recent weeks.

Reports that former AOL chief executive Jonathan Miller could be planning to buy a part of Yahoo or the entire business caused Yahoo's stock to rise by over 10 per cent this week.

Miller, who left AOL in 2006, is said to have been in talks with private investors for months in order to fund an acquisition of Yahoo at $20 to $22 (£13 to £15) a share. The price would value Yahoo at $28bn to $30bn (£19bn to £20bn).

However, other reports from close to Yahoo's headquarters in Silicon Valley suggest a different story.

According to Techcrunch founder Michael Arrington, the story in The Wall Street Journal is "incorrect".

"Our sources say that, while Miller and [former Fox Interactive Media president] Ross Levinsohn have been talking to Yahoo and Microsoft executives and shareholders for months about Yahoo's future (and at different times both Miller and Levinsohn have been proposed as Yahoo board members), they have not had any serious discussions with private equity funds about raising capital to take over the company," he said.

The rumoured Miller buyout follows another highly contested report about a Yahoo takeover in The Sunday Times on 30 November.

Also citing no sources, the paper said that Microsoft was in talks to acquire Yahoo's search business for $20bn (£13bn), marking its second attempt at acquiring the firm this year after Yahoo's rejection of its $44.6bn (£30bn) offer in February.

But Levinsohn has since denied the report to Silicon Valley blog VentureBeat, while Techcrunch again cast doubts on the facts.

Microsoft chief executive Steve Ballmer, meanwhile, emphatically denied any chance of new acquisition talks at a shareholder meeting in Washington.

If the report in The Sunday Times were true, this latest Microsoft takeover bid differs substantially from the first.

Rather than buying Yahoo's search business upfront, Microsoft would obtain a 10-year operating agreement to manage Yahoo's search division, while Yahoo would continue to run other parts of its business. Microsoft would also be given a two-year opportunity to buy the search business at a set price of $20bn (£13bn).

The new management team at Yahoo would include Miller and Levinsohn, according to the article.

Reports on Yahoo's fate have escalated in recent weeks, but the search firm continues to offer no confirmation. Rumours surfaced in late November that Yahoo was restarting talks to buy AOL to increase its gain on the search market. "We don't comment on speculation," said a Yahoo spokeswoman at the time; Yahoo repeated this assertion to vnunet.com in response to these latest reports.