The authorities are attempting to rescue the four people, who were taken by unidentified gunmen on 13 October, said Andrew Aniamaka, a spokesman for Delta state police.
Kidnapping for ransom is common in parts of Nigeria. In the past few years, a number of foreigners have been kidnapped in the Niger Delta region, which holds most of the country’s crude oil – Nigeria’s economic mainstay.
“The abductors have not made any contact but we are doing our investigations to know the motive and have them rescued without jeopardising their lives,” said Aniamaka.
“Information available to us shows they are missionaries giving free medical services,” he said, adding that the British nationals had been working in a very rural area.