MOSCOW, June 21 -- Against a backdrop of legal assaults on tycoons, harassment of free-thinking journalists and a general tightening of the state grip on things, Russia's leading pro-democracy political party now says federal intelligence agents are spying on it.

Russia's domestic intelligence agency, the Federal Security Service, has yet to comment on the accusation, posted on the Web site of Russia's Yabloko Party and echoed in a scathing letter from Yabloko's leader, the federal legislator Grigory Yavlinsky. But the charge gained weight this week when two St. Petersburg students who are Yabloko members claimed that federal agents tried to recruit them as political spies -- and, when the two refused, engineered their ejection from St. Petersburg's Baltic State Technical University.

The two students, both 20, were conditionally reinstated this week after their complaints became public.

The university rector, Yuri P. Savelky, asserted in an interview today that the entire affair was an innocent misunderstanding. But Yabloko's iconoclastic chairman, Mr. Yavlinsky, disagreed, noting that one student said the agents asked him about Yabloko's financing and his own ties to the West.

"Creating an atmosphere of surveillance and blackmail will lead to enormous losses for our country," Mr. Yavlinsky wrote in a letter, made public, to Nikolai Patrushev, the chairman of the security service, known everywhere as the F.S.B.

As if to underscore that, Yabloko and a new pro-democracy party, the Union of Right Forces, announced a quasi-merger today, a move aimed at strengthening Russian political support for a "civil society." The term, almost a mantra in Russian politics these days, connotes a land in which there is common agreement that everyone has to play by and obey the same rules.

Mr. Putin has been an ardent advocate of such a society, even as he has been roundly accused of subverting its most basic principles in places like Chechnya or with the skirmishing over media freedoms.

But as is true about much of what is unfolding in Russia these days, it is not at all clear whether Mr. Putin himself approved of or even knew about the security service's work. There is no doubt that various arms of the Russian government have heightened their scrutiny of potentially disruptive figures -- from Yabloko to the independent press tycoon Vladimir Gusinsky -- in ways that evoke unpleasant memories of Soviet repression.

But whether Mr. Putin is the mastermind of these forays -- or is fighting a rear-guard action against them -- no one outside the Kremlin appears to know. In the latest case, two 20-year-old students at Baltic State's aircraft and rocketry department, Dmitri Barkovsky and Konstantin Suzdal, claimed that they were approached in late May by two agents from the security service who asked questions about their studies, then gravitated to their political work.

"They started asking me about the structure of the Yabloko party and about different ways of financing Yabloko's election campaigns," Mr. Barkovsky, a fourth-year student at the university, said in an interview today. "I tried not to respond to their questions, but they started threatening me."

According to newspaper reports, the F.S.B. agents said Yabloko was spying for foreign powers and appeared to have more money at its disposal than might be expected of an independent political faction. Mr. Barkovsky, who calls himself an ardent Yabloko activist, later wrote a letter of protest to Mr. Patrushev, the security service's chairman, calling the pressure "persecution of my family for public expression of my political views."

A week after the meeting with security service officials on May 31, Mr. Barkovsky was barred from taking his exams at the university, and was shortly expelled. Mr. Suzdal, who could not be reached, also was removed from classes. In a conversation today, the university rector, Mr. Savelky, said both students had missed their final exams without explanation and had been failing classes because their political activity interfered with their studies.

Despite that, he said, F.S.B. agents had met with Mr. Barkovsky last month as part of a continuing effort to recruit "smart and well-educated students" to their ranks. "They probably had some problems and misunderstood each other," he said, "because as far as I know, there was a big scandal at the St. Petersburg F.S.B. office, and they are going to fire the officer who talked with him." Neither the St. Petersburg nor the Moscow F.S.B. spokesmen would comment today on any aspect of the controversy.

FSB Orders Students to Spy on Yabloko