Philippine investigators released seven people, including a Malaysian national, who have been questioned about the twin bomb blasts in Zamboanga City Wednesday night, according to the military officials Thursday evening.

At present, a Filipino Muslim is still under questioning over his alleged participation in the blasts, which authorities said could be designed by the notorious Abu Sayyaf group.

"We have released those whom we have invited for questioning since last night (Wednesday night). They were invited for questioning due to (their) suspicious characters," said a military official concerning the investigation.

As of the Malaysian national, the official said the foreigner was invited because of his transfer from one hotel to another before the blasts.

Meanwhile, Armed Forces Southern Command spokesman Domingo Tutaan Jr. said security has been tightened in southern Philippines following the twin blasts.

He said investigators have yet to positively determine those responsible for the terrorist attacks.

The government earlier Thursday made a statement condemning the bombings which occurred in a business district, wounding 14 civilians. No groups have claimed responsibilities for the attacks.

Source: Xinhua