An investigation is under way after carriages on an underground train in Glasgow came off the rails.

The accident happened shortly before 0700 GMT on Thursday.

The first train of the morning, with 12 passengers on board, was travelling on the inner circle between Kelvinhall and Partick.

A spokesman said two or three carriages were forced off the rails.

Passengers unhurt

It is not yet known whether the derailment was caused by broken rails or by something on the track.

No one was hurt, but the driver was sent home suffering from shock.

Those on board walked back along the tunnel to the platform after the accident.

Services have been disrupted and are not expected to be back to normal for the rest of the day.

The Railway Inspectorate is conducting an investigation at the site of the accident.