Trade unions are calling on brands and retailers sourcing garments from the Shenzhen Artigas Clothing & Leatherwear factory in China to step in to help settle a strike that has been going on for almost two weeks.

Almost 1,000 workers at the factory, which belongs to Hong Kong based Lever Style Inc, have been striking over unpaid social insurance and housing contributions since 10 December.

According to non-profit organisation Students and Scholars Against Corporate Misbehavior (SACOM), many of the workers have been at the factory for more than ten years, but Shenzhen Artigas has only contributed to the social insurance fund for five or six years.

Although workers are demanding compensation of the unpaid social insurance in arrears, Shenzhen has threatened to dismiss workers for taking part in the strike, SACOM added.

"We urge the brands to bear the responsibility because they failed to monitor the supplier to follow the law," SACOM said.

It later added: "We demand the brands to urge the factory to have equal negotiation with the workers' representative within this week and to ensure no retaliation against the workers by the factory. The brands should also proactively investigate into the workers' complaints regarding on their social insurance."

Japanese retailer Fast Retailing is one those sourcing from the factory. In a statement, the owner of casual clothing brand Uniqlo, said: "Although Fast Retailing is not in a position to comment on labour negotiations at its individual manufacturing partners, it ensures that appropriate working conditions are maintained at all of its manufacturing partners, and is thoroughly investigating the roots of the current dispute."

The company added that it will request that Shenzen Artigas Clothing & Leatherware "rapidly move to resolve the issue".

"Fast Retailing is committed to ensuring that all of its manufacturing partners adhere to their relevant labor regulations, and guarantee suitable working conditions."

Lever Style has three garment factories in Shenzhen and employs more than 4,000 people. It also has factories in other regions of China.

The latest dispute mirrors unrest earlier this year at Chinese footwear manufacturer Yue Yuen, where around 80% of its 45,000 workers went on strike to protest at the lack of payment of social security contributions. The Hong Kong-listed firm, which makes shoes for brands including Adidas and Nike, was subsequently hit by a US$27m loss as a result of production halting at its Gaobu factory in Guangdong province.