A British hostage kidnapped last month in southern Nigeria has been killed and three others freed.

Ian Squire was one of four Britons taken by suspected militants on 13 October from the oil-rich Delta area. The British High Commission and Nigerian authorities negotiated the release of Alanna Carson, David Donovan and Shirley Donovan.

The British Foreign Office (FCO) said it had been a “traumatic time” for those involved. An FCO spokesperson said that Nigerian authorities were investigating the kidnapping, adding: “Our staff will continue to do all we can to support the families.”

The four Britons taken hostage had all been working for a medical charity in the town of Enekorogha. Squire, an optician, had been administering free medical aid to local people.

It is believed the group were taken at about 02:00 local time on 13 October, when suspected militants stormed a rural community they were living in. According to reports, Dr and Mrs Donovan have lived in Nigeria for the past 14 years, running a charity called New Foundations, which gives aid to remote villages in the Niger Delta.