(Bloomberg) -- A Glencore Plc metals trader is one of a group of people detained by Chinese authorities this week as part of an investigation into shipments of lead into the country, according to people with knowledge of the matter.

Hu Qiang, a Beijing-based senior lead concentrate trader at Glencore, was detained by Chinese authorities, the people said, asking not to be identified because they’re not authorized to speak publicly. While a spokesman for Glencore declined to comment on any individual arrests, the company on Thursday said it refutes allegations that it acted improperly.

Nobody replied to calls or a fax to China’s General Administration of Customs. Hu didn’t answer calls to his mobile phone, which were diverted to voice mail, nor he did he reply to emails sent to his work address.

The Nanjing branch of China’s customs authority this week was said to have seized 16,000 metric tons of imported material that it says is lead slag but was declared as lead concentrate. The authorities allege that Glencore worked with a local company to import the material from Germany. The company said it refuted the allegations.

It’s another challenge for the world’s biggest commodity trader as it grapples with legal battles from Africa to Europe and faces the possibility of a bribery investigation by Britain’s white collar prosecutors over its work in the Democratic Republic of Congo with an Israeli billionaire.

The material was imported in three batches to the port of Lianyungang in Jiangsu province in December, people said on Thursday.

To contact the reporters on this story: Alfred Cang in Singapore at acang@bloomberg.net;Andy Hoffman in Geneva at ahoffman31@bloomberg.net

To contact the editors responsible for this story: Alexander Kwiatkowski at akwiatkowsk2@bloomberg.net, Pratish Narayanan

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