The addicts broke through the gates of the centre in Dong Nai Province on the evening of October 23 before heading towards the trans-Vietnam highway, said Huynh Van Tinh.

As of 11:00 a.m. on October 24, a total of 334 out of the 562 escapees had been rounded up, said Mr Tinh, who is director of the Dong Nai Province Department of Social Affairs.

A massive search is underway for the remainder.

A group who had recently been incarcerated at the centre led the escape and threatened to beat others if they didn't help break down the gate, said Mr Tinh.

Mass escapes from drug rehabilitation centres are not uncommon in Vietnam. 

In Vietnam convicted drug addicts must serve a mandatory two-year sentence at a state-run facility.

There are an estimated 180,000 drug addicts in Vietnam, most of whom abuse heroin or methamphetamine, according to official statistics.

Google Maps – The centre is 100 kilometres northeast of Ho Chi Minh City.