A British man said to have been kidnapped while carrying out missionary work in Delta State, South-south of Nigeria, has been killed by his abductors, a UK newspaper, The Guardian, has reported.

The victim, 56-year-old Ian Squire, was one of four British charity workers kidnapped from the rural community of Enekorogha on October 13, the paper reported on Monday.

It described the victim as an optician, who had been working with a Christian health charity, the New Foundations, to train local people to carry out sight tests and dispense prescription spectacles.

The New Foundations is reported to have opened an eye clinic in Enekorogha in 2016.

Mr. Squire is credited with developing a solar-powered, portable lens-grinding machine for the clinic, which is said to be located in an area without electricity.

Mr. Squire’s death, the paper said, has been confirmed on Monday by the UK Foreign Office.

The paper, however, said that the circumstances surrounding his death were not immediately clear.

The names of the other abducted missionaries were given as David Donovan, a General Practitioner from Cambridge, said to be the founder of the New Foundations; Mr. Donovan’s wife, Shirley; and Alanna Carson, an optometrist from Leven, Fife.

The three were released and have reunited with their families outside Nigeria.

The Guardian quoted an unnamed UK Foreign Office’s spokesperson as saying, “We are supporting the families of four British people who were abducted on 13 October in Nigeria, one of whom was tragically killed.

“This has clearly been a traumatic time for all concerned, and our staff will continue to do all we can to support the families. We are grateful to the Nigerian authorities, and are unable to comment given the ongoing nature of their investigations.”

The paper also published a statement issued by the families of the four hostages.

“Alanna, Ian, David and Shirley were kidnapped in Nigeria some three weeks ago. We are grateful for the support received by the British high commission and help from the Nigerian authorities in negotiating their release,” the families said.

“We are delighted and relieved that Alanna, David and Shirley have returned home safely. Our thoughts are now with the family and friends of Ian as we come to terms with his sad death.”

The late Mr. Squire was said to have set up his own charity, Mission for Vision, in 2003, and had been travelling to Nigeria since 2013 in a joint effort with New Foundations.

Mission for Vision, in its filing in the UK, said it was in the process of training three healthcare workers in the Delta.

The organisation has also done charity work in other African countries like Burundi, Ghana, Kenya, Uganda and the Democratic Republic of the Congo.

Kidnap-for-ransom has been one of the strategies associated with the militants in the Nigeria’s Niger Delta region who are agitating for the control of the oil deposits in the area.

The Guardian report didn’t, however, attribute the latest incident to any of the militant groups in the region.