* Fire service says flames being brought under control
* SSE says no impact on UK electricity generation, no injuries (Updates throughout)
LONDON, July 31 (Reuters) - Firefighters were bringing a blaze at Ferrybridge coal-fired power plant in northern England under control, operator SSE said late on Thursday, adding no injuries had been reported and there was no impact on the UK's electricity supply.
Two units generate electricity at the plant, known as Ferrybridge C, which with a combined capacity of nearly 1 gigawatt can power at least 700,000 homes.
"At around 2:00 pm (1300 GMT) today a serious fire impacted Units 3 and 4 of SSE's Ferrybridge C power station in West Yorkshire," the company said in a statement.
All personnel at the site have been accounted for, SSE added.
"Due to planned maintenance neither of the affected units had been operational over the summer and therefore had not been supplying power to the National Grid at the time of today's incident," SSE said.
SSE believes the fire started in Unit 4, but also had some impact on Unit 3.
The company said it will launch an investigation to establish the extent of damage but does not expect Unit 4 to return to service this financial year and Unit 3 will not come back online until November. It did not disclose when the planned maintenance had been scheduled to end. (Reporting by Nina Chestney; Editing by Dale Hudson and Keiron Henderson)