The United States expressed "grave concern" on Thursday, following reports that China is strengthening its nuclear arsenal, and called on Beijing to engage in dialogue to avoid a new arms race.

"Everyone's interest is that the nuclear powers will discuss directly with each other about reducing nuclear risk and (how) to avoid miscalculation," Robert Wood, the U.S. ambassador to the Geneva Disarmament Conference, told reporters.

Wood's remarks came in response to press reports last week that China was building more than a hundred new silos to launch intercontinental ballistic missiles.

The Washington Post, citing satellite imagery by the James Martin Center for Non-Proliferation Studies (of nuclear weapons), reported that 119 silos are built in the desert near the city of Yoman in northwest China.

Wood said it was "extremely disturbing."

"As long as China does not sit with the United States on a bilateral level, the risk of a destructive arms race will continue to grow and it will not benefit anyone," the US ambassador added.

The diplomat added that China claims to be a "responsible nuclear power" and that "its very, very small arsenal is for defense purposes only (…) but when you see a lot of what China does, it contradicts what it says."

Robert Wood spoke of a series of new weapons systems that China would seek to develop, including missiles capable of reaching the United States that could "completely change the dynamics of global strategic stability."

For the US ambassador, one of the main problems is the lack of transparency in this part of China, which does not provide details about its nuclear arsenal.