Minsk - A closed trial for four suspected Polish secret agents began in the Belarusian capital Minsk on Tuesday, the Belapan news agency reported.
The Belarusian citizens face charges of espionage, a crime potentially punishable by execution in the authoritarian former Soviet republic.
Viktor Veger, a Belarusian KGB spokesman, said the four will be accused of passing to the Polish secret service information about air defence installations, in particular Russian ones operating the S-300 anti-aircraft system.
Russia recently deployed the S-300 as a counter to the stealth technologies of the United States. The only country where the hi-tech missile system is in operation, aside from Russia, is in Belarus.
The leader of the spy ring was Vladimir Russkin, a Belarusian air defence officer, according to Veger.
News reports in the wake of arrests in mid-July listed five detainees: Russkin, retired Belarusian army intelligence major Viktor Bogdan; two Belarusian air force radio intercept specialists only by their last names Korneliuk and Petkevich, and a Russian army major with the last name Yuren.
Video tapes seeming to implicate all five in spying on Poland's behalf were aired on Belarus' state-run television channel shortly after the arrests.
Belarusian authorities reportedly turned Yuren over to the Russian government.
Polish diplomats in Minsk attempted to downplay the incident, saying they were unable to comment due to insufficient information about the detention and the trial.
Belarus' authoritarian President Aleksander Lukashenko has repeatedly accused Poland's government of working to undermine his regime by covert means.
Belarus' state-controlled media in 2006 accused diplomats in Poland's embassy to Minsk of acting as go-betweens between Belarusian dissident groups and western governments.
Belarusian security teams arrested Polish military attache Kasimez Witaschy in April 2004 on spying charges. He was ejected from Belarus a few weeks later.
c 2007 dpa - Deutsche Presse-Agentur