By Martin Plaut
BBC Africa analyst
A service has been held in London to protest against the treatment of the head of the Eritrean orthodox church.
Patriarch Antonios (l) used to have good relations with the president (r)
Patriarch Antonious is the head of two million orthodox believers and is a high-profile prisoner of conscience.
He was removed from his position earlier this year, after criticising the Eritrean government for interference in church activities.
Amnesty International says Eritrea displays one of the most extreme forms of religious persecution in the world.
The meeting heard that this was only the latest example of religious repression.
In 1994, followers of Jehovah's Witness - who refused military service on religious grounds - were stripped of all rights, including citizenship.
Then in 2002 the crackdown was extended to the evangelical churches.
And now the patriarch of the orthodox church, to which most Eritrean Christians belong, has been removed from his post and imprisoned after objecting to Eritrean government attempts to stop a bible-reading group.
The head of the British Orthodox Church, Metropolitan Seraphim, told the BBC he was very worried about his health.
"He's 79. He is known to have diabetes. And he's been kept in a darkened room in his residence and he complained on one occasion he was unable to even read his Bible."
Eritrea has a history of considerable religious tolerance between its Muslim and Christian communities, but the government comes from a Marxist-Leninist tradition.
The church says it believes quiet pressure has failed, and it will now take the issue of Patriarch Antonios to the British government.