UPDATE 1-Centrica's British Gas raises prices by 6 percent

* Domestic gas and electricity prices to rise 6 pct on Nov 16

* Average annual fuel bills will increase by around 80 pounds

* British Gas says faces rising wholesale prices and upgrade costs

(Adds detail, quote, share price)

LONDON, Oct 12 (Reuters) - Centrica PLC , the owner of British Gas, Britain's biggest energy supplier, is hiking its domestic gas and electricity prices by 6 percent next month, saying the "unwelcome news" for already tight household budgets was necessary to cover rising wholesale prices.

Annual dual fuel bills for British Gas customers will increase on average by around 80 pounds following the Nov. 16 rises, Centrica said in a statement on Friday.

The company said it was facing rising wholesale energy prices against a backdrop of dwindling North Sea gas supplies, as well as higher costs to upgrade the national grid and make it more energy-efficient.

"We know that household budgets are under pressure and this 1.50 pound per week rise will be unwelcome, said British Gas Managing Director Phil Bentley.

"However, we simply cannot ignore the rising costs that are largely outside our control, but which make up most of the bill."

British Gas said it was increasing the help available to customers to reduce their energy consumption, for example in improving their home's insulation.

"We need an energy efficiency culture in Britain today; rising prices don't have to mean rising bills. We are offering a huge amount of help to customers to help them cut the amount of energy they use and keep their bills under control," it said.

Shares in Centrica were down 0.7 percent in morning trading.

(Reporting by Natalie Huet; Editing by Paul Sandle)

((natalie.huet@thomsonreuters.com)(+44)(0)(207 542 1272)(Reuters Messaging: natalie.huet.thomsonreuters.com@reuters.net))