A WATCHDOG is set to block a price hike in water bills, saying it is unjustified.

Ofwat, the industry regulator, has decided to stop Thames Water's move to ask customers for an extra £29 next year, subject to a technical consultation.

The company, which is the main water supplier to south Bucks, has said it needs to cover a variety of costs but has failed to convince Ofwat that the eight per cent increase is correct.

Ofwat’s Chief Regulation Officer Sonia Brown said: “We said we would challenge Thames Water’s request.

“We have looked at the details and do not believe the current evidence justifies an increase in bills.”

Thames Water said it will review Ofwat's draft proposals and submit its response shortly.

A short consultation will take place giving Thames Water the chance to submit new evidence.

Thames Water has blamed rise in bad debt, costs associated with the 2011 transfer of private sewers, and buying land linked to the Thames Tideway Tunnel for the price hike.

A final decision is set to be made in early November.