Kuala Lumpur  - Malaysian police arrested 25 Chinese nationals believed to have been working as prostitutes since entering the country on social passes, reports said Sunday.

Police from the national headquarters anti-vice division launched a raid at a karaoke outlet in the northern Perak state Saturday morning, the Star daily reported.

Police also uncovered secret passages leading to various hideouts where the women were found hiding to evade detection, the report added.

"The raid was carried out following a public tip and our own investigations," a spokesman for the division was quoted as saying.

"They are suspected to be involved in immoral activities," the spokesman said, adding that the suspects have been handed over to the immigration department for further action. (dpa)