The electricity supply has been restored to 20,000 households and businesses in south Dublin after a fire at an ESB sub-station.

The alarm was raised shortly after 5.30am and the disruption to the power supply lasted for more than four hours for some customers.

The areas without power included: Blackrock, Booterstown, Foxrock, Sandymount, Leopardstown, Mount Merrion and Stillorgan.

Many street lights were knocked out and gardaí advised extreme caution on the roads as traffic lights were not working in the areas affected.

The fire broke out at a transformer in the sub-station at Brewery Rd in Leopardstown.

Three units of Dublin fire brigade attended the scene. 

Fire services said there were no reports of injuries.

ESB Networks said it expected the power supply to be restored by 10am.

Meanwhile in Limerick, 130 houses in Abbeyfeale were affected by a power cut.

The ESB said it expected power to be restored there by this afternoon.

It is not known what caused the power outage.