Vietnam, one of several countries in Asia where the death penalty remains in force, has been executing around 100 condemned prisoners a year by firing squad.

The switch to lethal injection will "reduce physical pain for the condemned and also provide psychological relief to executioners," police Major General Cao Ngoc Oanh was quoted as saying by the Nguoi Dua Tin ( newspaper on Saturday.

The administration is building chambers at prison facilities where the lethal injection will be administered to convicted prisoners, Oanh said.

Lethal injection is the principle method used in the United States to carry out the death penalty.

The Vietnamese police ministry first suggested an end to the firing squad in early 2006, saying it had led to mental disorder in the case of one member of the firing squad while many others had quit the service.

By Ho Binh Minh - Reuters - June 24, 2011