Scottish Power has said that it has not received any takeover approach after German utility giant E.ON said it was considering a bid for the utility firm.
Scottish Power is a major player in the UK energy market
E.ON, which already owns Powergen in the UK, said any possible offer for Britain's fifth-biggest energy group would be made entirely in cash.
News of E.ON's interest sent Scottish Power's shares up sharply on Monday, and on Tuesday they were 2.2% higher.
Scottish Power supplies energy to 5.2 million users in the UK.
In a statement issued on Tuesday morning, Scottish Power said "no approach has been made by E.ON".
E.ON said on Monday it was "considering its options" regarding a possible takeover for Scottish Power.
"No approach has been made to the board of Scottish Power and there can be no assurance that a transaction will be forthcoming. Any offer, if made, is likely to be solely in cash," the German company said.
Weekend newspaper reports suggested that E.ON had hired investment bank Lazard to advise it on a possible bid for Scottish Power.
Rival German utility group RWE and UK operator Scottish and Southern have also been reported as potential suitors for Scottish Power.
The Glasgow-based company has been refocusing its efforts on the domestic UK market in recent months.
Scottish Power is in the process of selling its PacifiCorp business in the US to energy firm MidAmerican.