Renewed speculation about a takeover bid for British Gas owner Centrica sent shares in the company soaring.

Centrica was the secondmosttraded stock on the London market after rumours placed European firms Norsk Hydro and Gaz de France as possible bidders.

Shares later cooled but still offered a boost for the company's 1.1 million shareholders, many of whom bought British Gas shares as a result of the Government's " Tell Sid" advertising campaign in 1986.

It is not the first time that Centrica has been seen as a takeover target, following speculation of a £19 billion merger with Norsk Hydro.

It is believed that talks foundered on opposition from the Norwegian government, which owned 44 per cent of the £11 billion-rated Norsk Hydro.

The latest bid speculation caused Centrica shares to close at 252.75p, giving it a market value of more than £9.2 billion. The company said it never commented on market speculation.

Thanks to a series of mergers and demergers, investors who bought a stake in British Gas in 1987 and held on to it will now have shares in three companies - Centrica, BG Group and National Grid.