The beheaded corpse of a British aid worker has been discovered in the Pakistani city of Quetta, almost four months after he was kidnapped.

The body of Khalil Rasjed Dale was left on a road outside the city, in southern Baluchistan province, with a note attachedwhich said he had been killed because a ransom had not been paid to his captors.

Dale, who had been working for the International Committee of the Red Cross (ICRC), was kidnapped in January while driving near the organisation's Quetta office.

He was abducted by gunmen as he made his way home in a clearly-marked ICRC vehicle on 5 January. His assailants are said to have bundled him into a car about 200m from an ICRC residence.

At the time, police in Quetta said Dale was abducted by unknown assailants driving a Landcruiser following a visit to a local school. He was travelling with a Pakistani doctor and a driver, who were not seized.

Quetta police chief Ahsan Mahboob said the killers' note read: "This is the body of Khalil who we have slaughtered for not paying a ransom amount."

Dale had been a Muslim convert for more than 30 years.

William Hague, the foreign secretary, said "tireless efforts" had been made to secure Dale's release and the British government had worked closely with the Red Cross.

"I utterly condemn the kidnapping and killing of Mr Dale and send my deepest condolences to his family and loved ones as they come to terms with their tragic and distressing loss," he said.

"We are devastated," said ICRC director general Yves Daccord. "Khalil was a trusted and very experienced Red Cross staff member who significantly contributed to the humanitarian cause.

"All of us at the ICRC and at the British Red Cross share the grief and outrage of Khalil's family and friends."

Separatist militants and the Taliban are extremely active in Quetta, which is just a couple of hours' drive to the border with Afghanistan's Kandahar province, where the Taliban is battling US forces.

The ICRC has working relations with movements such as the Taliban, but its staff remain vulnerable to criminals and kidnappers.

Retired nurse Sheila Howat, a former colleague of Dale's at Dumfries and Galloway Royal Infirmary, said: "It's dreadful what has happened to him, really awful. The world has lost someone who really cared for others."