Chinese scientists said Friday their independently developed robot helicopter, which can fly automatically without remote control, was ready for production.

The Shenyang Automation Institute under the Chinese Academy of Sciences has taken four years to develop two types of the robot.

The larger model at 3 meters long is almost the size of a small car, weighs 120 kg and has a payload of up to 40 kg. It can fly for 4 hours at a maximum cruising speed of 100 km per hour.

The smaller model weighs 40 kg and has a payload of 15 kg and maximum cruising speed of 70 km per hour.

Installed with a camera, the robot can hang in the air to catch aerial images, and search for or trace targets automatically.

Researchers in the institute said the robot could fly missions based on assigned coordinates and control programs, when wind gusts were below a velocity of force six (11 km per hour).

"They are fueled by petroleum and priced from 700,000 (102,000 U.S. dollars) to 2 million yuan," said Wu Zhenwei, a researcher at the institute based in northeast China's Liaoning Province.

"We do not have any marketing plan for the robot. But if there are orders, we can make small-scale production, like 20 to 30 units," he said.

Wu said the institute had no corporate partners for large scale production.

The robot project was funded by the central government and listed as a national key research project in 2006 because of its prospects for use in collecting information or carrying cargoes in harsh conditions such as earthquakes or poison gas leaks. It can also be used for spraying pesticides.