At least one person has been killed and 20 others injured after police in Cambodia clashed with protesting garment workers, according to rights groups.

Tuesday's protest took place outside the capital, Phnom Penh, where a bystander selling rice was struck by a bullet, the activists said.

Chan Soveth and Am Sam Ath of the rights group Licadho both confirmed a woman had been hit by a bullet.

Six protesters were injured, Chan Soveth said, adding that five Buddhist monks were hurt when police fired tear gas into a Buddhist pagoda where protesters had sought refuge.

Nine other people were hurt, including youths who jumped into the clashes and bystanders.

"The crackdown conducted by police this morning against workers was very cruel and unacceptable," said Kong Athith, a spokesman for the Coalition of Cambodian Apparel Workers Democratic Union, which organised the protest.

"Workers were unarmed. Why did police use live ammunition to crack down on them?"

Months of protests

Hundreds of workers from the SL Garment Processing (Cambodia) Ltd Factory clashed with hundreds of riot police sent to block a march from the factory to the Phnom Penh residence of Hun Sen, the prime minister, according to rights groups.

Workers from the factory, which makes clothing for Gap, H&M and other international brands, have been protesting for months for better working conditions and pay.

The violence erupted after police sent five officers to negotiate with the protesters, who surrounded and threatened to beat up the policemen, investigator Chan Soveth said.

It was unclear which side started the attacks, which included police firing live bullets and tear gas to rescue their colleagues, and protesters throwing rocks and wielding iron bars and wooden sticks, Chan Soveth said.

National Police officials could not immediately be reached for comment.

The garment industry is Cambodia's biggest export earner, employing about 500,000 people in more than 500 garment and shoe factories. In 2012, the Southeast Asian country shipped more $4bn worth of products to the United States and Europe.

Pay is low and working conditions are usually uncomfortable. In May, the ceiling of a Cambodian footwear factory collapsed, killing two people and injuring seven. 

Source: Agencies