A fire in an electrical sub station left the Olympiad leisure centre and around 30 other nearby buildings without power for around seven hours on Monday.

The Olympiad was forced to close after the fault in the Southern Electric equipment turned off all the lights.

"We would like to apologise to the customers who were affected," said a spokesman from Southern Electric.

"It was a long time for them without electricity. We did the repairs and upgraded the equipment."

The fault emerged at about 11.15am when a member of the public spotted arcing flying sparks at the sub station close to the Olympiad.

A small fire started in a cabinet at the sub station and the firefighters were called out.

They were not needed, however, as the fire went out and was entirely contained within the cabinet, the spokesman said.

Southern Electric maintenance staff were hard at work on repairs throughout the day and power was restored at 6.15pm.

Although the cause of the fault is not known Southern Electric speculated the amount of electricity being used in the area might be to blame.

"It may be demand has crept up," the spokesman said. "The new equipment will be more than man enough to cope with it we like to take the belt and braces approach."

A spokesman for the Olympiad said the leisure centre closed all day, and did not reopen in the evening when the power was restored.

"We do not know the full figure for what we lost," she said.

"Obviously we did lose money because of a day's closure but I couldn't put a figure on it.

"Like other customers of Southern Electric, the power cut has to be of a certain length before we are entitled to claim any compensation."