Chinese state media accused seven detained labour activists of "meddling" in employment disputes and "seriously disrupting social order" on Wednesday, as an uptick in labour protests coincides with slowing economic growth.

One of the accused, Zeng Feiyang, the director of labour rights group the Panyu Workers' Centre, was detained earlier this month in southern China along with at least two other activists, the Hong Kong-based China Labour Bulletin (CLB) reported.

"Workers' representatives believe that the true intentions of Zeng Feiyang et al is to incite workers to strike, create social impact, interfere with factories' normal production and disturb social order," the state-run Xinhua news agency said. The report also accused him of accepting overseas funding.

The crackdown on labour activists comes as the southern province of Guangdong, one of China's richest, confronts growing economic challenges as many factories in the Pearl River Delta close or relocate to cheaper Chinese provinces -- or countries such as Vietnam where labour costs are lower.

Workers are often left with unpaid wages and no redundancy pay.

"This campaign of arrests against groups of workers' rights activists in Guangdong is unprecedented," CLB spokesman Geoffrey Crothall told AFP at the time of Zeng's detention, adding that the crackdown was "very alarming".

"But the authorities will not solve any problems by putting these activists in jail. This will only aggravate the distress and discontent of workers."

Zeng stands accused of receiving more than five million yuan in funding from foreign organisations over several years, and for passing reports and photos of strikes on to foreign organisations and media, who "upgraded, exaggerated and distorted" labour incidents to "opportunistically blacken China's national image and attack China's social system", Xinhua added.

Foreign ministry spokesperson Hong Lei said that relevant authorities would deal with the situation "in accordance with the law" at a regular press briefing on Wednesday.

Zeng had been helping workers in the southern province of Guangdong win payment of wages and unpaid benefits in disputes against employers.

The six other detained activists were named by Xinhua as Meng Han, Tang Huanxing, Zhu Xiaomei, Peng Jiayong, Deng Xiaoming, and He Xiaobo.

Chinese NGO Weiquanwang (Rights Defence Network) reported earlier that He worked with an organisation which helps workers suffering from occupational injuries.

The CLB said He and Zhu were arrested with Zeng earlier this month.

Independent trade unions are banned in China, with only the official All-China Federation of Trade Unions legally recognised. However, critics say it often fails to assist workers in disputes.

Since President Xi Jinping came to power in 2013, Beijing has taken a harder line towards rights groups. Xi has overseen a crackdown on dissent that has seen hundreds of lawyers, activists and academics detained in recent years, with dozens jailed.