DUBAI (Reuters) - Bahrain said on Thursday it had foiled an attempt by “terrorist fugitives” wanted in connection with a January prison break to flee by sea to Iran.

Security forces foiled the “trafficking” attempt in a dawn operation, a statement published on the interior ministry’s Twitter account said.

“Preliminary joint investigation indicates the fugitive boat was heading to Iran,” the message said, adding further details would be announced later.

The ministry said in January that one policeman was killed when armed men attacked Jau prison in Bahrain, freeing several convicted inmates, describing the incident as a terrorist act.

Thousands of mainly Shi’ite Muslim Bahrainis are in jail on charges ranging from participating in anti-government protests to armed attacks on security forces in the Western-allied Gulf kingdom, where the U.S. Fifth Fleet is based.

Bahrain earlier this month executed three men convicted in the death of three policemen, including an Emirati officer, in a 2014 bomb attack. Bahrain accuses non-Arab Iran of fanning unrest and supporting militants involved in armed attacks in the island kingdom. Iran denies any involvement.