A train has been derailed by debris on the track near Bargoed following a landslip. Network Rail say around 10 people were on board at the time but nobody was injured. Buses are replacing trains between Bargoed and Rhymney.
Service is suspended on Arriva Trains Wales between Bargoed and Rhymney because of a derailment at Brithdir.
Inspector Michael Edwards from the British Transport Police says cable theft is "an attractive proposition for would-be thieves", but that the police are cracking down on it.
Rail services on the Rhymney valley line to and from Cardiff have been severely disrupted today because of a cable theft. The incident has already caused around 800 minutes of delays and many cancellations according to Network Rail.