MOSCOW, OCT. 17 -- An investigative reporter with Moscow's most popular newspaper died in a bomb blast today in what Moscow authorities called "an unprecedented terrorist act," escalating the growing violence against journalists in the former Soviet republics.

Dmitri Kholodov, 27, who had reported on corruption in the military and other sensitive topics, was killed in his office in the Moskovsky Komsomolets newsroom by a powerful explosion that also damaged the walls and slightly injured another reporter.

The blast occurred shortly after Kholodov returned to the newspaper with a briefcase that he had told colleagues he would be collecting from a source in Russia's domestic intelligence agency, his editor said tonight.

"This is a political crime against journalists and against freedom of speech," said Pavel Gusev, the newspaper's editor in chief. "There are forces who want to intimidate journalists and teach them not to stick their noses into where it smells of big money and big crime."

With crime and corruption blossoming at many levels of Russian society, contract murders and beatings have become commonplace. Bankers and businessmen are often targets, but prosecutors, officials and journalists also have been attacked with growing frequency.

Last year, 25 journalists were killed and another six disappeared in Russia and other former Soviet states, according to the Fund for the Protection of Glasnost, an advocacy group to defend press freedoms.

Still, the apparent murder of Kholodov was the most brazen attack yet, reaching into the heart of a newspaper that has become a symbol of the new Russia by virtue of its audacity, iconoclasm and cynicism.

Russian President Boris Yeltsin was "revolted" by news of the killing and ordered his interior minister to conduct an investigation, the president's spokesman said. Moscow authorities called the explosion "the first act of planned terrorism carried out against a journalist in the capital" and said it was "unprecedented in cruelty and effrontery."

Kholodov had worked at the newspaper for four years, covering all the "hot spots" of civil war in the old Soviet orbit, including Tajikistan, Georgia and Chechenia, Gusev said. "He went everywhere; he flew everywhere; he covered everything."

Recently, the reporter had been investigating alleged arms trafficking by Russian army officers while based in Germany. He had received several death threats in connection with these reports, Gusev said.

Kholodov had told colleagues that an employee of the Federal Counterintelligence Service, a successor to the KGB, had been talking with him for some time and had finally agreed to give him documents. The reporter said he had been told the documents would be left for him in a luggage locker at a Moscow railway station.

Gusev said tonight that he does not know whom Kholodov met, if anyone, in the train station. But he said the reporter returned with an attache case, which contained what the editor called a professionally made bomb.

"We will take revenge, not by maiming or burning people, but by continuing to write," Gusev said.

One Moscow newspaper, Nezavisimaya Gazeta, runs a monthly chronicle of beatings and killings of journalists in former Soviet republics. Its report for September said none had been killed last month but that four were beaten and eight were investigated by government officials. Alexei Simonov, chief of the Fund for the Protection of Glasnost, said journalists have become vulnerable mostly because they receive no protection from authorities. He said police take no interest in reports of beatings and in some cases are themselves guilty of attacks on reporters.