Centrica's British Gas to cut nearly 700 jobs

(Adds Prime Minister, Union comments, background)

LONDON, April 20 (Reuters) - Utility group Centrica (LSE: CNA.L - news) 's British Gas, the country's largest energy supplier, said on Wednesday it was proposing to cut 684 jobs at its British Gas Services by closing its Oldbury office near Birmingham.

Centrica, which has been hit hard by weak energy prices and fiercer competition, announced last year it would cut 6,000 jobs as part of a cost-saving drive.

Of these job cuts, 3,000 are expected this year and 800 took place in the first quarter, Centrica said earlier this week.

In February British Gas announced 500 job losses in its insulation business.

"We must also respond to the changing needs of our customers, and they increasingly want to contact us online," said Claire Miles, British Gas's managing director of customer operations.

Oldbury employees will now discuss the proposal under a 45-day consultation process, British Gas said.

If the site is closed it will try to redeploy staff in other offices, it added.

"We will make sure that a taskforce of ministers is available to talk to the company, to talk to the local community, to provide all the assistance in terms of retraining and other things that can be done to help," said Prime Minister David Cameron in answer to questions in Parliament on Wednesday.

Labour union GMB, who said most of British Gas's Oldbury staff were members of its union, vowed to fight to protect every job. (Reporting by Karolin Schaps; Additional reporting by William James; Editing by Greg Mahlich)