Thousands of homes were still without power last night after a suspected arson attack caused a huge blackout across Birmingham.

About 30,000 homes and businesses were plunged into darkness in the early hours when a 40ft blaze erupted at a substation containing 11,000 volt cables.

A spokeswoman for electricity company Central Networks said the fire was thought to be started by vandals throwing burning car tyres into a sub-station.

Fifty firefighters from across the West Midlands were called to tackle the fire which broke out inside a corrugated steel tunnel in Watson Road East, Saltley.

Thick, black smoke billowed from underground ductings which carry the cables to one of the main sub-stations in Nechells.

Power was cut in 27,000 homes in Ward End, Aston, Washwood Heath, Bromford, Nechells, Alum Rock, Hodge Hill and Bordesley Green after fire broke out at around 11.45pm.

For most of yesterday afternoon, 8,000 homes were still without electricity in Ward End, Aston, Nechells, Wash-wood Heath, Bromford and Erdington.

By 7pm a remaining 2,000 homes were still without power and generators were being brought in as a temporary supply.

When the fire broke out, traffic lights went out, entertainment complex Star City was evacuated and Heartlands Hospital switched to an emergency supply.

A spokesman for Birmingham Chamber of Commerce said most businesses were at least fortunate in that it happened late at night on a Sunday.

"Anything like this disrupts production," he said. "If vandals were to blame, it was an appalling thing to do."