SHANGHAI — Around 300 workers at Shenzhen Artigas Clothing & Leather, an apparel factory that supplies Uniqlo, have been on a hunger strike since Saturday evening, according to reports in local Chinese media.

The reports said 13 individuals were arrested when workers and their supporters marched on local government offices Monday.

Loy Wong, from the Hong Kong Confederation of Trade Unions, which has organized a petition for the workers, confirmed reports of unrest at the factory. He was not able to confirm the scale of the unrest or further details.

“Some of the workers have been detained by the police. Yesterday they went to the government office to protest and were taken to the police station. We also have sources saying some workers are holding a hunger strike inside of the factory,” he said.

Calls to Shenzhen Artigas Clothing & Leather for comment went unanswered.

According to Wong, the situation at the company reflects current moves from Hong Kong and Pearl River Delta area governments to try and upgrade their manufacturing base, pushing lower value factories further inland.

“When a factory needs to relocate, workers will look at the social benefit they should be paid by their employers. From previous cases we have seen factories often try to escape their legal responsibilities. They are meant to pay benefits on top of the basic wages, but they commonly don’t,” he said.

According to local press reports, workers are upset with the factory’s plans to relocate.

“We have no option, no place to go. All the relevant departments we have tried to get them to manage this issue but no one can help us, we can find no one, only despair. The bosses have the money and the power, the government helps him and backs him up, we are suppressed by the police. It’s desperate,” a worker, calling herself Xiao Feng, told Chinese media from inside the factory.

A spokesman for Uniqlo’s parent company, Fast Retailing, confirmed that the Japanese company’s manufacturing partners in Shenzhen are investigating the situation.

“While we are in the process of confirming the facts related to the strike, we have requested the management of Lever Shirt Ltd. [owner of Shenzhen Artigas Clothing & Leather] to discuss this matter with the workers and reach a peaceful resolution,” the statement said.

Earlier this year, SACOM, a Hong Kong-based advocacy group, issued a report saying that employees at two of Uniqlo’s Chinese suppliers, Dongguan Tomwell Garment Co. Ltd. and Pacific (Pan Yu) Textiles Holdings Ltd., were working excessive hours in unsafe conditions, including extremely high temperatures, poor ventilation and floors covered with sewage. In response, Fast Retailing said it launched its own investigation and warned the factories to improve working conditions.