Renewed clashes between security forces and protesters erupted Monday after thousands of workers rallied outside a factory making clothes for US sportswear company Nike.

Violence flared as police tried to break up a confrontation between those on strike and those who are working at the Taiwanese-owned Sabrina Cambodia Garment Manufacturing factory in Kompong Speu, reports the BBC.

Police moved in after protesters demanding higher pay threw stones at the factory, triggering a fight with workers opposing the strike. At least eight people were detained by police.

“We had to break them up in order to protect the factory,” said Kheng Tito, spokesman for the national military police.

The incident comes after a similar clash last week when police allegedly used stun batons to disperse female protesters who had gathered outside the factory, leaving at least 23 workers hurt, including a pregnant woman who suffered a miscarriage.

Protests began May 21 when workers demanded a pay increase from $74 to $88, Son Vanny, organizer of the Free Trade Union, said.