China is expanding its nuclear capabilty: US scientists

US scientists have claimed in a report that_ China is expanding its capacity to store and launch nuclear missiles.

Satellite images from Xinjiang province in the west of the country suggest it is building a nuclear missile silo field_ the report from the Federation of American Scientists (FAS) says. US defence officials have expressed concern about China's nuclear build-up.

It is the second new silo field reported to be under construction in western China in the last two months. The site could house about 110 silos_ which are underground facilities used for the storing and launching of missiles.

Last month_ the Washington Post newspaper reported 120 silos spotted at a site in a desert area in Yumen_ in Gansu province.

The FAS said in its report on Monday that the new site at Hami_ about 380 km (240 miles) north-west of Yumen_ was at a much earlier stage of development.

In 2020 the Pentagon said China was set to double its stockpile of nuclear warheads_ from a low base. The news comes as the US and Russia prepare for arms control talks.

The talks_ between US Deputy Secretary of State Wendy Sherman and Russian Deputy Foreign Minister Sergei Ryabkov_ are being seen as a first step towards reviving stalled negotiations on reducing nuclear arms. But China has so far not taken part in arms control negotiations.

The US Strategic Command_ the part of the Department of Defense responsible for strategic deterrence_ voiced its concern about the report in a tweet.

"This is the second time in two months the public has discovered what we have been saying all along about the growing threat the world faces and the veil of secrecy that surrounds it_" it said.

The silo field in Xinjiang was detected using commercial satellite imagery_ but higher-resolution pictures were later provided by Planet_ a satellite imaging company.

In 2020 China had a nuclear stockpile of more than 200 warheads and was aiming to at least double this amount_ the Pentagon said.

The US has approximately 3_800 warheads_ analysts say.