The United States has turned its only remaining air base in Central Asia into a state-of-the-art surveillance center to spy on China and Russia, a new documentary claims.

The documentary, called "Base", shown on Rossiya TV, showed a compound of two-storey windowless buildings at Kyrgyzstan's Manas base, stating: "In one of the buildings ... there is a multi-channel, multi-functional system of radio-electronic surveillance".

"This station can eavesdrop on the whole world - every fax, every e-mailed letter. Every call from a mobile or landline phone is being recorded and processed. Billions of messages are being intercepted," it said.

"At Manas, the US built a station which controls Central Asia, parts of China and Siberia. For Americans, the existence of the intelligence complex at the base is more important than a mere runway."

Peng Guangqian, a senior Chinese military expert, said: "There are two kinds of data collection - legal and illegal ones. Apparently what the US base is doing is beyond what the law allows."

If proven true, it reflects Washington's double standard on data collection, Peng said, and such action under the flag of combating terrorism will actually hamper its task.

Sun Zhuangzhi, an expert on Central Asian studies with the Chinese Academy of Social Sciences, said the timing of the documentary by Russia's state TV station possibly signals a confrontation between Russia and the US in this region.

A US defense official told Reuters last Friday that the TV report surfaced just as US and Kyrgyz officials had resumed dialogue over the base's future.

After it secured a $2-billion economic aid package from Russia, Kyrgyzstan told Washington in February to close the base near its capital Bishkek, which the US uses to send supplies to troops in Afghanistan. The Americans are due to leave in August.

In the past year, US Congress and civil think tanks have repeatedly criticized China's "growing cyber warfare capability" and alleged Chinese hacking into computers of other countries, which the Foreign Ministry dismissed as fabrication driven by Cold War mentality.

"With the most abundant funds, the most advanced technology and a global data collection network, the US occupies the big chair in world data collection work. It has no right to judge others in that regard, especially on fabricated events," Peng said.

Chen Xuehui, an expert on international military studies with the Academy of Military Science of the People's Liberation Army, said the spying is one of the factors that make China, Russia and other countries unwilling to join the US in military cooperation on anti-terrorism activities in Afghanistan.

"Though China and Russia support combating terrorism, as it's in the interests of the two countries and the region, they're concerned whether Washington would use it for its own interests," he said.

Such espionage will damage trust and hamper the fight against terrorism, a key task of the US government, he added.

The film was made by Russian journalist Arkady Mamontov, who in 2006 provoked a spat between London and Moscow with a documentary showing pictures of what Mamontov said were British spies using a fake rock to gather secrets electronically.