Around 450 Vietnamese drug addicts have escaped from a rehabilitation centre where many were held for compulsory treatment, an official said Thursday.

The detainees attacked guards, climbed walls, and broke down the main gate at the centre in the Vietnam's southern province of Ba Ria-Vung Tau late Wednesday.

"We have brought 150 patients back, while search efforts are underway for nearly 300 others," Le Thi Trang Dai, director of the provincial labour department, told AFP.

Vietnam's government enforces a compulsory treatment programme for the country's estimated 140,000 drug addicts.

Addicts can also voluntarily enter the centres to undergo rehabilitation treatments.

The escapees were a mix of compulsory and volunteer admissions, Dai said.

Local authorities are urging families to bring back runaway patients so they can complete their treatment, she added.

"Police are also investigating the reasons behind the escape, trying to understand if there is a leader behind the incident," she said.

The escapees have been begging for clothes from local residents and trying to hitchhike out of the area, the VnExpress newspaper said.

"Others have escaped into (a) nearby deep forest," the report added.

Addicts undergo two-year spells of treatment at the centres aimed at curbing rising drug use rates, especially among young people.