GOPENG, Nov 23 ― A Cambodian woman and her six-year-old son were among 20 illegal immigrants arrested during a joint sting by traffic police, immigration, drug agency and land transport authority here today.

The woman and her child were found with valid travel documents but without the official stamps to show where they entered country, Perak police contingent traffic enforcement chief of staff Assistant Superintendent Mohd Ariffridzuan Ezahar said.

Investigations are underway to find out the entry point for the two Cambodians, he added.

The other 18 illegal foreigners detained were from Bangladesh, Indonesia, Vietnam, Myanmar, Pakistan and Cambodia.

The four-hour joint operation northbound of Km290 of the Gopeng RTC started at 10am with the inspection of 145 lorries and buses in total.

Ariffridzuan said 190 summonses were issued in the operation which ended at 2pm.

"We also found three lorry drivers, aged between 40 and 45, whose urine tested positive for drugs,” he said, noting that two of them tested positive for heroin while another tested positive for syabu.

A total of six officers and 74 personnel from police, Immigration Department, National Anti Drug Agency and Land Public Transport Commission took part in the operation.