More police departments across China have begun to use drones in their operations, according to their equipment suppliers.

"Several local police departments are in talks ... on drone procurement because we offer them a wide range of advanced products," said Li Chen, a designer of unmanned aerial vehicles at China North Industries Group Corp, one of the country's biggest defense companies.

Although he refused to name the police departments, he said that "they plan to use the drones to perform air patrol, reconnaissance, traffic monitoring and riot control operations".

Speaking at the sixth China International Exhibition on Police Equipment and Anti-Terrorism Technology and Equipment in Beijing, Li said: "Though police authorities in some cities have started to use drones, many others are still waiting for, or selecting, a suitable model for their air operations. There are only a handful of drones in the market that are specifically designed for the police, so the market has huge potential."

Among Chinese police authorities, those in Shandong and Shaanxi provinces are heavy users of drones, he said.

More than 300 police equipment and security technology companies from 13 nations and regions including China, the United States and Germany showcased their products and technologies at the three-day exhibition, which opened on Wednesday and was organized by the Beijing Public Security Bureau and the China Association for Science and Technology.

Li's company brought several advanced drones that were developed for the police and boast world-class technology.

"We have light-duty drones that are very convenient to carry and use. If the police need to conduct long-distance, long-duration tasks, we also have large drones capable of carrying 100 kilograms of equipment, and they can stay in the air as long as four hours," the designer said.

Wang Xin, a sales manager at Beijing Xinyuandun Public Security Technology Development Center, said the private company has sold fewer than 20 drones to police departments in various regions.

"Our drones were used by the police during a recent national event," he said, declining to disclose details because his company signed a confidentiality agreement with the police.

When police buy drones from his company, they usually purchase two drones and a host of auxiliary apparatus such as ground-control devices and target trackers, he said.

Despite no official statistics revealing how many drones are in service with China's police, earlier reports indicated that they have become very popular among public security authorities across the nation.

Police in Beijing have sent drones to detect opium poppy plantations on a regular basis since 2010.