* GMB union says strikes set for Sept 8, 15, 22
* Action centred at Macclesfield manufacturing site
* Workers protesting over plan to freeze pension scheme
LONDON, Aug 24 (Reuters) - Union members at AstraZeneca will take accelerating strike action on three days next month over a plan to freeze the pharmaceutical group's final salary pension scheme, the GMB union said on Tuesday.
The action will involve three two-hour strikes on Sept. 8, three four-hour strikes on Sept. 15 and a 24-hour strike starting at 0500 GMT on Sept.22. Further action will be announced in due course, the GMB added in a statement.
"The last thing our members want to do is to take strike action at AstraZeneca but the attack by the company on the pension entitlement of our members leaves them with no choice," said GMB National Officer Allan Black.
"The strike action follows a GMB ballot of its members in the company in the light of this highly profitable pharmaceutical company's decision to make savage cuts in its employees' defined benefit (sometimes called final salary) pension scheme."
About 2,500 workers are affected by the changes, mainly based at Macclesfield in northern England, the company's second largest site.
AstraZeneca said last week it was reviewing a ballot by union memebers backing strike action, which it said resulted in about a third of GMB members, and less then 2 percent of its UK employees, voting in favour.
Final salary pensions are becoming a rarity for British workers, as companies move to cheaper defined-contribution schemes that limit their future financial exposure. (Reporting by Ben Hirschler; Editing by Louise Heavens)