The Home Office is not confirming or denying whether any British workers have been involved.
But officials say they are investigating reports which suggest at least one Briton was taken when gunmen stormed a compound belonging to a Lebanese construction company in Nigeria.
ITV News reporter Sejal Karia talks from outside the Foreign Office:
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The true number of those believed to be dead or missing and presumed dead following the fire won't be known until the end of the year.
Low pressure will keep much of the British Isles under cloud with many seeing periods of steady rain throughout the rest of today.
Michael Bond, the creator of Paddington Bear has died at the age of 91.