A Sudanese journalist working for an Arab television network is being held in the U.S. military compound for terrorists, his editor says.

Cameramen Sami Al-Haj from the al-Jazeera network was picked up crossing between Afghanistan and Pakistan in December, says Brahim Helal, al-Jazeera's editor-in-chief.

His whereabouts were unknown until his wife received a letter from him. It was sent from the U.S. prison in Guantanamo Bay, Cuba, where the U.S. holds terrorist suspects for interrogation.

"I know him personally," and do not think he is a terrorist, Helal told CBC's As It Happens.

The network sent U.S. authorities a letter including Al-Haj's prison number, but has had no reply, he said.

U.S. military spokesperson Lt.-Col. Colonel Bill Costello said he could not comment on individuals, but it can take a long time interrogating someone to establish whether the story they're telling is true.

"There are cover stories that need to be unwoven," he said.