CONSUMER groups are worried the potential new owners of Thames Water could be under pressure to create high profits following an £8bn takeover.

Water bills in Oxfordshire will not immediately be affected because bidders, Australian banking group Macquarie, must stick to prices fixed five years in advance by the regulator, Ofwat.

Macquarie will inherit the limits to annual price rises until 2010 agreed with the current owner, German group RWE.

But Andrew Marsh, of the Consumer Council for Water, said: "RWE have gone back to Germany with a very hefty £500m profit, but they have a very patchy record.

"Customers will be very concerned that they haven't seen any of the benefits that shareholders have reaped."

In a statement, RWE said its management board had agreed on the £8bn sale, which must still be approved by directors and by competition authorities.

Ann Robinson, of Internet site uSwitch.com, said: "Our concern is that with a sale price of £8bn, Thames Water's eight million customers will come a poor second to the new owner's shareholders."