Several Radio Free Europe Web sites were knocked off the Internet a week ago in a distributed denial-of-service (DDoS) attack that the news organization's spokesman compared to attempts decades ago by the Soviet Union to jam the US-funded group's radio signals.

The attack, which started on April 26, hit Radio Free Europe's Belarus Web site hardest and was timed to coincide with protests there that day to mark the anniversary of the 1986 Chernobyl nuclear disaster, the organization claimed. Seven other Radio Free Europe (RFE) sites, including those in Kosovo and Azerbaijan, as well as the Russian-language site, were also affected.

"We had restored service on all but the Belarus site late Monday morning," Martins Zvaners, a Washington-based RFE spokesman, said Friday. "The Belarus site was up again on that afternoon."

Radio Free Europe and an associated service, Radio Liberty, are news organizations funded by the US Congress that date back to 1949, when RFE began broadcasting news to radio listeners in Eastern Europe and the USSR at the beginning of the Cold War. The organization still uses radio to distribute its news, but it also relies on the Internet.

The incident was the largest attack RFE had ever experienced, said Zvaners. "It was massive, and it was distributed," he said. At its peak, the DDoS attack was sending more then 50,000 requests to the RFE sites, which overwhelmed its servers' capacity and essentially knocked the sites offline. Other Belarusian sites were also hit, including the Minsk-based nongovernmental organization (NGO) Charter 97.

Within an hour of RFE issuing a news release on Monday detailing the attack, "the bogus requests petered out," said Zvaners.

RFE has taken steps to protect against similar attacks in the future, but Zvaners would not get specific. "Our network [administrators] are looking at ways to better protect our sites from future attacks," he said.

April 26 was the 22nd anniversary of the meltdown at a nuclear reactor near Chernobyl, Ukraine. A plume of highly radioactive fallout drifted to the northwest, over what is now Belarus and toward Finland and Sweden. Large areas of Belarus, Russia and Ukraine were contaminated, but the majority of the fallout landed in Belarus.