Rights activists on Friday urged Belarus's KGB security services to reveal the location of a well-known defence journalist who went missing more than a week ago and is suspected to have been detained.

Alexander Alesin, a journalist at the independent newspaper Belarussians and the Market who specialises in defence and the arms trade, has not come to work since November 26 and his cell phone is switched off, his colleagues said.

Journalists and activists have sounded the alarm over Alesin's disappearance, saying they fear he has been detained by security forces in the secretive ex-Soviet state which is ruled by strongman Alexander Lukashenko.

The Vyasna human rights organisation and the Belarussian journalists' association issued a joint statement saying "We call on the KGB to inform the public about the reason and place of the detention of Alexander Alesin... and also the nature of the charges against him."

The deputy head of Vyasna, Valentin Stefanovich, told AFP: "We think it's unacceptable when information about the location of a detained person, his judicial status and the article of the criminal code under which he is charged are a secret and the public has no access to them."

"The KGB is a state organ, so let them say: 'Yes, he is in the KGB prison on suspicion of such-and-such a crime.' We are waiting for this information."

The opposition news site Charter 97 suggested Thursday that Alesin could been arrested on suspicion of espionage, citing colleagues who wished to remain anonymous.