Media playback is unsupported on your device Media caption Protesters clash with police outside the factory

Police in Cambodia have clashed with thousands of workers outside a factory making clothes for the US sportswear company, Nike.

Violence flared as police tried to break up a confrontation between those on strike and those who are working.

The striking workers want the owners of the factory outside the capital Phnom Penh to increase their pay.

Cambodia's garment industry employs hundreds of thousands of people and is the country's biggest export earner.

Police said they intervened after protesters threw stones at the factory in Kompong Speu and fighting broke out between rival groups of workers.

"We had to break them up in order to protect the factory," said police spokesman Kheng Tito.

He said that 20 officers had been injured by stones and sticks.

Son Vanny, organiser of the Free Trade Union (FTU), said its members exchanged barrages of sticks and stones on Monday with workers opposing the strike, after which riot police moved in.

The FTU said at least 10 people were injured and seven workers arrested, although police would not confirm any arrests.

The Taiwanese-owned Sabrina (Cambodia) Garment Manufacturing factory employs more than 3,000 workers, mostly women.

Protests began on 21 May when workers demanded a pay increase to the equivalent of $88 (£57.34) per month from $74.

There were violent scenes at the factory last week when police allegedly used stun batons to disperse protesters who were blocking a road.

Nike, for whom the factory is a contractor, expressed concern after that incident, AP news agency reported.