MANILA, Philippines - An anti-corruption group is calling on the House of Representatives to investigate Ilocos Sur 1st District Rep. Ronald Singson, who was arrested in Hong Kong on drug charges.

The Center for Anti-Graft and Corruption Prevention (CACP) said the House needs to prove that it will not tolerate drug use, particularly among its members.

"Responsibilidad nilang imbestigahan si Singson para mapalitan siya. 'Di biru-biro na makulong siya ng five to eight years," Lane Afable, CACP secretary-general, said.

The group is also asking all lawmakers to undergo drug tests. Some lawmakers, including Senator Vicente "Tito" Sotto III, have expressed willingness to undergo testing.

Afable said drug testing on lawmakers is in accordance to President Benigno "Noynoy" Aquino III's clean governance program.

The CACP head added that congressmen should make an effort to prove that not all congressmen are drug users.

However, House Majority Leader Neptali Gonzales said that the mandatory drug test could violate the Constitution.

Gonzales added that the proposed drug probe would have to wait until the House ethics committee is formed.

Singson was arrested at the Customs arrival hall of Chek Lap Kok International Airport last July 11 for possession of 26.1 grams of cocaine and 2 tablets of diazepam, more commonly known as Valium.

A copy of Singson's charge sheet obtained by ABS-CBN News showed that Singson has been charged with trafficking of a dangerous drug.

Under existing law, suspects summarily convicted of bringing 10-50 grams of illegal substances such as cocaine or heroine to Hong Kong could be fined HK$500,000 (P2.9 million) and imprisonment of 3 to 8 years. This is the minimum penalty for Singson if he pleads guilty and is convicted of the crime. – with a report from ANC