Thousands of Cambodian workers protested Wednesday against the arrest of strikers during a police crackdown at a factory making clothes for US sportswear giant Nike, unionists said.

Cambodia's workers are seeking to flex their muscles over discontent at low wages and tough conditions in the multibillion-dollar textile industry, which produces goods for top western brands.

Eight workers were arrested on Monday at the sportswear factory when riot police broke up a demonstration calling for higher pay, but the charges against them have not yet been announced, Free Trade Union secretary general Say Sokny told AFP.

About 2,000 to 3,000 garment workers rallied outside the Kampong Speu provincial court in southern Cambodia demanding their release, she said, as riot police stood by.

At least 10 workers were hurt during the crackdown, which followed violent scenes at the same factory last week when riot police allegedly used stun batons against strikers, who have now been protesting for more than a week.

A pregnant woman suffered a miscarriage in that incident, according to protesters.

Days later, three people were knocked unconscious after police fired water jets at a protest in Phnom Penh over disputed land, adding to activists' concerns over the kingdom's tough stance towards dissent.

Rights groups said the crackdowns suggest Cambodia's government is seeking to silence its critics before elections due on July 28, with strongman premier Hun Sen looking to extend his near three-decade grip on power.

"The government fears the protests will lead to social unrest because of the upcoming election and what happened in the Arab world and recently in Turkey," Ou Virak, president of the Cambodian Centre for Human Rights, told AFP.

"But the government's iron-fisted action will only cause anger," he added.

Cambodia's textile industry employs about 650,000 people and is a key source of foreign income for the impoverished nation.