LONDON (Reuters) - The storm that swept across southern Britain on Monday morning caused nuclear power outages at the Dungeness B21 and B22 units, operator EDF Energy said.

EDF Energy said on its website that both units, which have a capacity of 550 megawatts (MW) each, came off at 0744 GMT on Monday, adding that unit availability was expected to be zero for the next seven days.

"The shutdown was weather-related. The plant reacted as it should and shut down safely," an EDF Energy spokeswoman said.

The company said in a separate statement that both reactors were shut after power to the site was cut off.

"The station is liaising with National Grid regarding returning the power supply," the statement said.

A strong storm battered southern parts of England and Wales early on Monday, with wind speeds reaching almost 100 miles per hour, cutting power supplies to around 220,000 homes, forcing flight cancellations, disrupting trains and closing many roads and bridges.

(Reporting by Henning Gloystein; and Alexander Winning; editing by Tom Pfeiffer)