Spanish police have broken up an alleged extortion ring run on mobile phones by four prisoners from a jail in the Chilean capital, Santiago.

The police said the prisoners had cold-called random numbers in Spain and terrorised people by telling them they had kidnapped their family members.

Police said they had received more than 160 complaints.

They said around 10% of those called had paid up to see the release of their relatives.

Most who had paid up were older people, police said, adding that some had handed over $12,000.

The gang had relied on preventing the targeted caller from hanging up the phone and on creating high levels of panic so that they would give in quickly and pay up.

It is believed the prisoners were helped by relatives and neighbours outside the prison to arrange the money transfers.