The Eastern Sabah Security Command (ESSCOM) has stepped up security measures, with heightened alert from the military and police, in the 10 districts placed under the Eastern Sabah Security Zone (ESSZONE).

This follows a clash Sunday night between armed followers of the Moro National Liberation Front (MNLF) and Philippine troops in Zamboanga City.

ESSCOM director-general Mohammad Mentek said although the battle took place far away from ESSZONE, the security command was not taking it lightly.

"We have already put on alert our security assets and personnel...we are not taking chances on possible intrusions, following that clash.

"That's why, we put our security forces on heightened alert," he told Bernama here Monday.

Mohammad was asked to comment on the clash between armed followers of the MNLF and Philippine troops on Sunday night.

A Philippine news portal in Mindanao quoted Mayor Isabelle Climaco-Salazar Monday, as saying that armed followers of the MNLF had held some 20 civilians hostage in Zamboanga City after a clash with government troops on Sunday night.

Climaco-Salazar said the MNLF members were planning to enter the city and declare independence at the City Hall, adding that a crisis committee was formed to handle the situation.

Meanwhile, Mohammad rubbished claims in The Philippine media Sunday that MNLF had activated about 4,000 foreign-trained Tausug fighters embedded in Sarawak and Sabah in Malaysia.