A miniature of China's lunar rover Yutu is on display at a market in Yiwu, Zhejiang province, on Jan 21. Lyu Bin / for China Daily

As space engineers try to repair the Chinese lunar rover Yutu, which has suffered a mechanical glitch, marketing managers and lawyers of the lunar exploration program are also busy, as they fight an invasion of pirated space products.

A Chang'e Aerospace Technology lawyer who requested anonymity told China Daily that 16 companies, all registered in Beijing, have been found selling products falsely identified as licensed or falsely claiming to be licensed partners.

Products made or sold by the companies include watches and models of the Yutu lunar rover, the lawyer said, adding that all the companies claim they had the authorization of the nation's space agency.

However, none of them has a license from Chang'e Aerospace Technology, which belongs to the State Administration of Science, Technology and Industry for National Defense - the only holder of the Chang'e-3 mission's trademark rights, he said.

"Some of the companies even ran advertisements in newspapers and websites and on television to promote their goods," the lawyer said.

Local commerce watchdogs have taken measures to crack down on the rampant piracy and fraudulent promotions.

The commerce bureau in Deyang, Sichuan province, is investigating a consumer's complaint that he bought unlicensed models from a company in Shenzhen, Guangdong province, whose sellers told him they had authorization.

Chang'e Aerospace Technology has also filed a complaint with the State Administration for Industry and Commerce, asking the administration to stop the unauthorized use of its trademarks and manufacture of pirated products.

Meanwhile, sales of authorized lunar rover models in Yiwu, Zhejiang province, a hub for the manufacture of small commodities, have been doing well since December.

Ye Ming, general manager of Zhejiang Jinghui Giftware in Yiwu, said more than 160 Yutu models were sold within the first eight hours after the launch of the Chang'e-3 probe, racking up sales of more than 160,000 yuan ($25,900). Ye said the model is manufactured by a company authorized by Chang'e Aerospace Technology.

"Customer enthusiasm is as high as we could have ever imagined. Even before Chang'e-3 launched, a businessman from Wenzhou had already booked 50 models from me," Ye said.

By the end of last year, the company had sold more than 30,000 Yutu models, and foreigners are also among the customers. "We have not started exporting the models yet, but there are customers from the Middle East," Ye said.

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