Requiring drivers to wear helmets would be a "simple and extremely effective" way to save lives, said Hans Troedsson, the World Health Organization representative in Vietnam.

"Vietnam should make helmet-use mandatory on all roads," Troedsson said at a press conference in advance of the UN's Global Road Safety Week, which begins next Monday.

Motorbikes were involved in 75 percent of Vietnam's 12,300 road deaths last year, an increase of 10 percent from 2005, according to the National Traffic Safety Committee.

Vietnam approved a helmet law several years ago, but the poorly enforced measure only required drivers to wear helmets on highways, not city streets.

Vietnam's economy is booming and the number of vehicles on the chaotic roads is rising quickly. Motorbikes account for more than 90 percent of Vietnam's vehicles, but the number of cars is increasing rapidly.

Each year, traffic accidents kill 1.2 million people and injure or disable between 20 million to 50 million more worldwide, Troedsson said.

"Unless drastic measures are taken to counter the trend, the number of deaths and disabilities from road crashes will continue to increase," he said.