Russian hackers have succeeded in crippling another central Asian country, after a Russian "cyber militia" knocked Kyrgyzstan off the Internet, according to a security researcher.

The move demonsrates that the hackers are able to respond even faster than last year, when they waged a digital war against another former Soviet republic, Georgia.

Since 18 January, the two biggest Internet service providers (ISPs) in Kyrgyzstan have been under a "massive, sustained distributed denial-of-service attack," said Don Jackson , the director of threat intelligence for SecureWorks.

The attacks, which are ongoing, have knocked most of the country offline and disrupted email to and from a US air base there, Jackson said. The public affairs officer at Manas Air Base in Kyrgyzstan was not immediately available to answer questions about whether the attacks have disrupted operations or other activities.

According to Jackson, the distributed denial-of-service (DDoS) attacks - essentially a flood of requests that overwhelm servers and effectively knock them off the Internet - can be traced to the same groups of Russian and ethnic Russian hackers who assembled in militia-like fashion last August to launch similar attacks against Georgia.

"The traffic we've collected has all the hallmarks of the tools that were used in the Georgia attacks," said Jackson. "And they're from the same network [of IP addresses] that we associated with the cyber militia last year." Researchers have also found two groups, led by "two specific players," in common with the 2008 attacks against Georgia, he added.

Speculation about why Kyrgyzstan's Internet infrastructure was attacked centre around an investment deal that Russia is negotiating the country.

Russia has indicated that it wants Kyrgyzstan to oust foreign air forces, including the US', before it will agree to loan the country $300 million (£212 million) and invest another $1.7 billion in its energy industry.

Opposition to the current Kyrgyzstan administration has relied heavily on the Internet, while President Bakiyev's government has ignored the web, said Jackson. "Any attack by Russians would do no collateral damage to their ally in the area, and would only impact the opposition," he explained.

Beyond the immediate impact on Kyrgyzstan, what's worrisome to Jackson is the speed with which this attack was mounted.

"To put some perspective on this, it's been an escalating pattern from Estonia to Georgia to here," he said, talking about the 2007 and 2008 attacks against other former Soviet republics. "The attacks are more closely coinciding with events that are core to the Russian interest, with increasingly fast response and quick mobilisation.