The president of Soviet Kazakhstan asked the Kremlin on Friday to declare an ecological disaster in part of his republic after a Sept. 12 explosion at a nuclear fuel factory released a cloud of toxic gas, Tass reported.

The blast and fire at the Ulbinsky metallurgical plant in a workshop using beryllium spewed the toxic gas that affected "a considerable part of the population of Ust-Kamenogorsk," a city in eastern Kazakhstan near the border with China and Mongolia, the official news agency said.