Britain says Eritrea has released four British nationals it accused of spying and kept in detention for five and a-half months.

Britain's Foreign Office said Sunday that the four men have been able to leave the east African country and will be reunited with their families. It thanked the government of Qatar for facilitating their return.

There was no immediate word on the men's condition, nor any statement from Eritrean or Qatari officials.

The four men worked for the British security firm Protection Vessels International. They were detained in a boat off the Eritrean coast on December 24.

On Thursday, Eritrea accused the men and the company of committing acts of espionage, and said they had set up an arms depot on the Eritrean island of Harmil.

Their detention had strained the already cold relations between Eritrea and Britain. Britain says Eritrea denied its officials consular access to the men.

Protection Vessels International says it provides security for boats traveling through the pirate-infested waters of the Indian Ocean and the east coast of Africa.