China 'carries out nuclear test in desert - then tries to hide it from the world'

The 1998 treaty has not been ratified by some major nuclear powers, including the United States, China, and Russia.

Thomas DiNanno, the US Undersecretary for Arms Control and International Security, first laid out the accusations at the Disarmament Conference in Geneva earlier this month.

He said: "I can reveal that the US Government is aware that China has conducted nuclear explosive tests, including preparing for tests with designated yields in the hundreds of tons."

Dr Christopher Yeaw, an Assistant Secretary of State, said he had reviewed further data and concluded a mysterious earthquake must have been a nuclear explosion.

A magnitude 2.75 quake was detected in Lop Nur, China by a monitoring station in Kazakhstan.

Dr Yeaw said China then attempted to conceal the test using decoupling - where a device is detonated within a large underground chamber to reduce the magnitude of the shockwaves.

He said: "There is very little possibility I would say that it is anything but an explosion, a singular explosion."

He added that it was not consistent with mining blasts, adding "it is... what you would expect with a nuclear explosive test".

The Comprehensive Test Ban Treaty Organisation (CTBTO), established by the UN to enforce the nuclear test ban treaty, said there was not enough evidence to confirm that it was a nuclear blast.

The CTBTO said its international monitoring system did pick up on two "very small" seismic events. 12 seconds apart, at 9.18am GMT.

Robert Floyd, the executive secretary of the CTBTO, said: "The IMS is currently capable of identifying events consistent with nuclear test explosions with a yield equivalent to or greater than approximately 500 tonnes of TNT.

"These two events were far below that level. As a result, with this data alone, it is not possible to assess the cause of these events with confidence."

The CTBTO added it could add additional verification systems until all countries had ratified the treaty.

The Chinese Government has denied the claims and said it was an excuse for the United States to continue its own nuclear testing.

Chinese embassy spokesman Liu Pengyu said: "This is political manipulation aimed at pursuing nuclear hegemony and evading its own nuclear disarmament responsibilities."

He added: "China urges the US to reaffirm the five nuclear-weapon states' commitment on refraining from nuclear tests, uphold the global consensus against nuclear tests, and take concrete steps to safeguard the international nuclear disarmament and non-proliferation regime."

In October, President Donald Trump ordered the Pentagon to begin nuclear tests despite the treaty.

The White House has pushed for a three-way treaty between itself, Russia, and China, to replace New Strategic Arms Reduction Treaty (New Start), which came to an end earlier this year.

It said China has more than 600 nuclear warheads, and could have more than 1,000 warheads by 2030.