Gunmen free Briton in Nigeria
Diplomats say the hostage was very sick and rebels feared he might die.
The diplomat had no news of the American hostage, identified by industry sources at the time of the kidnap as Bill or Billy Graham.
He was also unable to say if the Briton had already been evacuated from southern Nigeria.
The past few weeks have seen both a sharp increase in hostage-takings in the Niger Delta region of Nigeria. The attacks are carried out by a mixture of separatist groups with a political agenda and criminal gangs lured by ransom money.
Twenty-nine foreigners are currently being held. Twenty-five of them are Filipinos, one seized from a company car on Wednesday and another 24 crew seized earlier from a cargo vessel; two are Italians and the remaining two are a Lebanese national and the American who was seized along with the Briton.
Nine Chinese oil workers from the China National Petroleum Corp (CNPC) kidnapped on January 25 were freed on Sunday.
Nigeria, which derives more than 95 per cent of its foreign exchange earnings from oil, lost more than half a million barrels a day last year to unrest in the delta.