The operation to remove a derailed train from tracks near Castlerock on Northern Ireland's north coast is continuing on Wednesday.

Twelve people were treated in hospital after the derailment on Tuesday.

The line is likely to be closed for several days - a bus service is operating between Coleraine and Londonderry.

The accident is believed to have been caused by a landslide.

The train driver and seven passengers were injured when the 1250 BST Londonderry to Belfast train came off the line as it was approaching the Downhill tunnel near Castlerock on Tuesday.

Translink's Ciaran Rogan said there would be a thorough investigation into the accident.

The carriages were thrown onto an adjacent road

"It could have been a lot more serious," he said.

"Fatalities could have occurred not only on the railway but also on the road and we will be taking it up with the landowners of the land adjacent as to exactly what their management and maintenance routine was for the cliffs here."

A police spokesperson said recent heavy rain was believed to be responsible for the landslide which saw rocks and boulders land on the track and two adjacent public roads.

The train was approaching downhill when the driver saw a boulder on the track. He applied the emergency brake, but could not stop the train in time.

Leg injuries

Twenty-one people, including the driver, were on board the three carriages when they were derailed.

Six are being treated in the Causeway Hospital in Coleraine.

Two others were released after treatment.

The driver, who is the most seriously hurt, is being treated for leg injuries.

One of the carriages was forced onto the beach adjacent to the track.

When we look at the scale of the problem here, we could have been talking about fatalities

Gregory Campbell East Londonderry MP

Among those taken to hospital were five people suffering from angina, one of whom is an 84-year-old woman.

They had complained about chest pains and are being kept in hospital for observation.

East Londonderry MP Gregory Campbell said more needed to be done to make everyone that comes into contact with the railways aware that such a thing could happen.

"When we look at the scale of the problem here, we could have been talking about fatalities," he said.

The DUP assembly member added: Any measures that can be put in place, although it is difficult to legislate for this sort of thing, I am sure will be put in place immediately."