China and Russia have signed an agreement on the sale of Russia's S-400 surface-to-air missile system, a senior manager of Russia's leading technology corporation said on Wednesday.

In addition, Russia is planning to use China's spacecraft equipment, Dmitriy Shugaev, deputy CEO in charge of international affairs at Rostec, a State-owned company in charge of Russia's arms exports, told China Daily.

He said that the S-400 deal "is important to both Russia and China" and China will be the first foreign user of the missile system, but he declined to reveal the deal's details, saying they "are too sensitive to be revealed".

According to Russian media reports, the S-400 is a new-generation air defense system capable of engaging any aerial target, including airplanes, helicopters, drones and cruise and tactical ballistic missiles. The system's 40N6 missile can destroy airborne targets up to 400 km away.

China clinched the deal in September last year, at a cost of more than $3 billion for the delivery of an unknown number of S-400s, Moscow Times reported.

Currently, China relies on its domestically developed HQ-9 and the Russian-made S-300 missile systems for mid- and long-range air defense.

Wu Peixin, a military observer in Beijing, said that as one of the world's best anti-aircraft weapons systems, the S-400 will give the People's Liberation Army a big boost to its long-range, high-altitude air defense network.

"The system has several types of missiles that are capable of intercepting cruise missiles and tactical ballistic missiles, which means it is suitable to be deployed around important governmental or military sites to safeguard those vital places," he said.

Vasily Kashin, a senior analyst at the Moscow-based Center for Analysis of Strategies and Technologies, told Russia's Sputnik news agency that the long range of the S-400 will allow the PLA to engage targets over the East China Sea. "These missiles are capable of shooting down targets in the Diaoyu Islands airspace from the Chinese mainland."

Shugaev, the Rostec deputy CEO, said Russia is in negotiations with China Aerospace Science and Industry Corp and China Aerospace Science and Technology Corp on the procurement of China-developed spacecraft instruments such as electronic and satellite communications devices.

Spokesmen for the two Chinese companies could not be reached for comment.

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