LONDON, Aug 20 (Reuters) -
* A 24-hour strike at Total’s Alwyn, Elgin and Dunbar offshore platforms started on Monday at 0500 GMT as planned, according to the Unite union, which is pushing for a revamp of working rotas.
* Further strike dates to stop operations for 12 hours at a time are set for Sept. 3, Sept. 17, Oct. 1, Oct. 15 and Oct. 29.
* A 12-hour strike on Aug. 13 contributed to a near 4 percent rise in prompt British wholesale gas prices.
* Previous stoppages have had limited effect on oil supplies as they were mitigated by draws on stored crude. (Reporting by Shadia Nasralla, editing by Louise Heavens)