BONN, JULY 31 -- The Red Army Faction, the West German terrorist group once known as the Baader-Meinhof gang, said today that it intends to launch a guerrilla war against the rising power of a unified Germany.

The terror group -- which last Friday blew up the car of State Secretary Hans Neusel, West Germany's top anti-terrorism expert, slightly injuring him -- today accused the "rising Greater German-West European world power" of creating a "Fourth Reich" that would spread repression through economic domination.

In a five-page letter to news organizations, the group, which has attacked leading West German political and business figures since the mid-1970s, said that Neusel represented "the continuity of German fascism from the Third Reich to 'Greater Germany.' "

Terrorism experts here said the letter appears to be authentic. They said that although the Red Army Faction is believed to consist of a core group of fewer than 25 members, it has loose ties to other terrorist and anarchist groups around Western Europe.

One former West German anti-terrorism official said tonight that the Red Army Faction's message "shows that they are desperate, that time has just about run out for them and no one really cares about their message." The faction, the expert said, is made up mostly of middle-aged ideologues who failed to grow out of their anarchist subculture of the late 1960s.

Andreas Baader, who set fire to a Frankfurt department store in 1968 to "liberate" his countrymen from consumerism and sexual repression, joined Ulrike Meinhof, who helped him escape from prison, to form a gang that terrorized West Germany for most of a decade. Their followers formed the Red Army Faction.

The letter said the group intends to step up its activity because "only an armed action can get this stalled situation going again."

Since the two German states agreed to reunite, East Germany has disclosed that its former Communist government sheltered eight Red Army Faction members, providing them with new names, housing, and protection from prosecution. In recent weeks, the eight suspected terrorists have been arrested and sent to West Germany for prosecution.

West Germany's Interior Ministry predicted earlier this month that the faction would attempt new terrorist acts to prove itself as a continuing threat to the stability of German society.

Today's note indicated that is the faction's intent. It said that after starting two world wars this century, "the third attack by German capital on the peoples of Europe will not be made by military means, but by means of economics and politics."

The note called on other "revolutionary forces" to join a "long struggle" now necessary because "imperialism has won the Cold War."

According to federal prosecutor's office spokesman Hans-Juergen Foerster, the letter was similar to one sent to news organizations last November, claiming responsibility for the car bomb that killed Alfred Herrhausen, the chairman of Deutsche Bank, West Germany's largest.

Today's letter said the bombing Friday in Bonn -- a 55-pound bomb triggered when a car blocked a light beam across a highway exit ramp -- was meant to kill Neusel, but failed because "we calculated the amount of explosives too low."