A picture displays the geographic features of a beach in Dongying, Shandong Province. The State Administration of Science, Technology and Industry for National Defense released a set of high-definition pictures taken by Gaofen-1, on August 16, 2014. [Photo: Chinanews.com]

Chinese police have detected dozens of cross-border tunnels in northwest Xinjiang Uygur Autonomous Region and the northeast area neighbouring North Korea, with the help from a satellite, according to the National Space Administration.

But it's not clear whether the police have found out the reasons behind the tunnels.

Earlier, there were reports about illegal crossings on the China-North Korea border, while some terrorists snared in Xinjiang were found to have been trained abroad.

The watchdog said the Gaofen-1, a high-definition earth observation satellite, has also helped police spot illegal poppy and marijuana farms in Heilongjiang, Hebei, Jilin provinces and Inner Mongolia Autonomous Region and an offshore depot storing smuggled oil off Fujian province.

The Gaofen-1, the first of China's HD observation satellite series, was launched in April 2013 and has provided massive information to the country's public security, land management, environment and agriculture departments.

Its upgraded version, Gaofen-2, blast off on August 19. It can detect a one-meter-long object in full color on the ground.