The number of thefts of nuclear materials has risen considerably in Russia in the last couple of years, but none of the cases involved weapons-grade plutonium, Interior Ministry officials told a press conference Tuesday.


Interior Ministry general Andrei Terekhov said 27 cases of theft of radioactive materials were detected in 1993, and 16 cases last year. He said there have been nine recorded thefts of radioactive substances over the first nine months of 1995.


Speaking at the same press conference, Sergei Korolyov, spokesman for the Interior Troops Commander, said the ministry had sent an additional 6,000 servicemen in 1994-1995 to guard nuclear sites.


Terekhov said investigations had shown that most stolen substances involved stable uranium and sources of ionizing radiation, which can be used in transducers or other equipment and installations at nuclear power stations.


He said most of the substances were stolen from Nuclear Power Ministry facilities by underpaid technicians. "There is no organized nuclear trafficking mafia in Russia," Terekhov said.


"The radioactive materials seized have a very low content of Uranium-235, which is used for producing nuclear weapons," said Georgy Kaurov of the Nuclear Power Ministry. To be used to make a nuclear bomb, the substances would need to be at least 97 percent enriched with that type of uranium, he said.


World attention on nuclear smuggling from Russia reached a peak a year ago, when German undercover agents offered smugglers $260 million upon delivery of four kilograms of Russian plutonium, enough for a crude bomb.


On Aug. 10, 1994, one of the smugglers landed at Munich airport on a flight from Moscow with a briefcase containing 363 grams of 88 percent fissionable Plutonium-239.


In a separate operation, almost three kilograms of highly enriched uranium was confiscated in Prague in December 1994.


Russian officials have consistently denied that the uranium in question originated in Russia. Nuclear Power Ministry officials said requests had been sent to both Munich and Prague for analysis of the confiscated materials, but these were not provided. "We are ready to carry out an expert investigation to determine the radioactive material's origin," said Kaurov.