KUALA LUMPUR, Sept. 11 (Xinhua) -- Two Indonesian fishermen were kidnapped in waters near Malaysia's Sabah state, police said Tuesday.

The two were onboard a fishing vessel when they were kidnapped in the early hours of Tuesday in the waters off Semporna in Sabah, said acting Sabah Police chief Omar Mammah.

Another two escaped by hiding inside the ship and later reported to police, said Omar, adding that the masked kidnappers were believed to have carried rifles.

The police have not received any request for ransom and are investigating whether the suspects are related to the Abu Sayyaf group, he said.

According to local media, this would be the first kidnapping incident in almost two years. Kidnappers of Abu Sayyaf and other militant groups based in the restive southern Philippines have in years abducted local residents and foreign tourists in the neighboring Malaysian state Sabah for ransom.

The Malaysian authorities have strengthened security, imposing curfew in some areas.