Chinese police have detected dozens of cross-border tunnels with the help of a high definition satellite in troubled Muslim-majority Xinjiang province as well as northeast area bordering North Korea.
The tunnels are a cause of concern for China as Xinjiang, where militants of the al-Qaeda linked East Turkestan Islamic Movement (ETIM) are staging violent attacks in recent months, bordered Pakistan-occupied Kashmir (PoK) and Afghanistan.
China has deployed security forces in a large scale to quell the spread of the outfit.
Xinjiang is restive for the past few years over protests by native Uygur Muslims objecting to the increasing settlements of Hans.
It is not clear whether police have found out the reasons behind the tunnels, state-run broadcast CRI reported.
Jiang Zhaoyong, a Beijing-based expert on ethnic affairs, told South China Morning Post that identifying these passageways may alleviate pressure on border patrol forces.
Jiang noted that some people may have used such routes to leave China and receive terrorism training abroad, but given that Xinjiang's border measures about 5,600km, "it's wrong to think that will spell the end of terrorism around Xinjiang."
Much of the bases of ETIM militants existed in Pakistan's troubled tribal areas as well as Afghanistan.
The Gaofen 1 satellite can identify objects as short as two metres wide. It is part of a seven-satellite network that will be fully operational by 2016 and provide global coverage.
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 report said.
China National Space Administration which released the pictures taken by Gaofen-1, a high-definition earth observation satellite, also spotted vast stretches of 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 marijuana plantations could be the biggest illegal marijuana plantation in recent Chinese history, officials said.
But most significantly the photos were provided by The Gaofen-1, the first of China's HD observation satellite series, which was launched in April 2013.
It has provided massive information to the country's public security, land management, environment and agriculture departments. Its upgraded version, Gaofen-2, which can detect a one-meter-long object in full colour on the ground, was deployed on August 19.
The new satellite has security implications for India and neighbouring countries as it provides pictures with greater clarity at the borders.
China has rarely revealed the use of satellites in sensitive areas such as defence and national security.
"It is impressive that they have made so many discoveries in less than a year," the Post quoted an unnamed Chinese space scientist as saying.