The men faced a walk of five or six miles through rebel-held territory before reaching a checkpoint manned by Nigerian peace-keepers. Only then could their release and safety be guaranteed, said the source.
It was believed that some of the 20-odd hostages still held by the Armed Forces Revolutionary Council would remain in captivity after the release of the Britons, which was negotiated by a special British-United Nations mediation team.
Earlier the intermediary who brought back 19 hostages from the rebel stronghold in the Occra Hills on Sunday had returned "hopefully to get the rest", according to the Foreign Office. The three British officers, part of the United Nations observer mission in the West African country, were held with up to 24 other people. Among those released earlier were two British officers, and it became clear that nearly 50 people had been abducted.
They were taken last Wednesday during an observer mission to the Occra Hills where they were due to oversee the handover to aid workers of several hundred child prisoners.
The hostages were held by a group from the Armed Forces Revolutionary Council (AFRC), which wants to know that its leader, Johnny Paul Koroma, is not a prisoner of the main rebel group, the Revolutionary United Front (RUF).
According to some reports, which were not confirmed by the Foreign Office, the AFRC was sending four men to Monrovia, the capital of neighbouring Liberia, to see Mr Koroma. The hostage-takers wanted guarantees of Mr Koroma's freedom and their own safety, and better recognition under a peace deal for Sierra Leone, which they feel favours the RUF.
The Britons freed on Sunday were named as Lt-Col Ian Howard-Williams and Major Justin McEwan.Reuse content