Cuban human rights activist Elizardo Sánchez Santa Cruz says the secret police harassed him for the first time in 20 years, and dissident Guillermo Fariñas says they hit him, in what the two men called yet another sign of the government’s growing nervousness over the opposition.

Sánchez has been one of the few critical voices that seemed to be tolerated by the communist government. He has run the Cuban Commission for Human Rights and National Reconciliation from his home in Havana without trouble since 1992 even though it has never been recognized by officials.

But he alleged that two State Security agents in plainclothes who approached him on a street Tuesday called out his name, accused him of being a “liar” and a “mercenary for Washington” and threatened that “soon I will receive a forceful reply from the revolution.”

“This was very rare,” he told El Nuevo Herald. “The truth is that I have not been molested” since a 1992 police raid on his commission’s offices. “Monitored yes, but molested, no.”

Sánchez blamed the incident on “the increasing nervousness in the government” over continuing opposition activities despite a harsh crackdown over the past year by the Raúl Castro government.

Sánchez’s commission reported earlier this month that police carried out 5,625 short-term arrests — usually lasting only hours — for political motives in the first 10 months of the year, a monthly average of 562 that compared to 172 in 2010 and 343 in 2011.

Dissidents also have complained of increased beatings, and some have been jailed for longer periods. Antonio G. Rodiles, one of the most active dissidents in recent times, was beaten during his arrest and held for 19 days earlier this month.

Fariñas, who won the European Parliament’s Sakharov prize for Freedom of Thought in 2010, said he believed the attack against him showed authorities are “in a state of nervousness” because dissidents will not halt their work despite the repression.

He was walking to a friend’s home in Havana Tuesday night when two men in their 20s who were dressed in civilian clothes called him a “mercenary” and “counterrevolutionary” and tried to hit him on the head with a stick, he said. He put up his arm and the blow landed on his forearm.

The two men then ran into a dark-colored Lada, a Soviet-era car traditionally used by State Security agents, and a third man at the wheel sped away, Farinas told El Nuevo Herald.

Cuban officials claim that dissidents are paid by the U.S. government for their opposition and brand them as mercenaries. Dissidents say they oppose the Cuban government because of its human rights abuses and communist system.

Sanchez said he sent a telegram to Interior Minister Gen. Abelardo Colomé Ibarra, in charge of the secret police, denouncing his harassment “in an aggressive and humiliating form.’’ He said the two men “made various threats against my integrity.”

“Arbitrary detentions, physical aggressions, threats and humiliations against peaceful citizens are counterproductive as an alternative to the national dialogue… that could help reverse the grave and growing crisis affecting the great majority of Cubans,” he added.

Fariñas said State Security officials have told him in previous encounters that some of the best known dissidents on the island cannot be detained without the express approval of Castro, Colomé or Gen. Carlos Fernandez Gondín, the head of State Security.

“That these things are happening now to Elizardo and I indicate to us that the situation is getting tough,” he added. “Well, if martyrs are needed, if it’s the turn of Guillermo Fariñas or Elizardo Sanchez, we accept that.”

Fariñas has launched more than two dozen hunger strikes during his years as a dissident and independent journalist. Several of them have landed him in the hospital.

The InterAmerican Press Association, meanwhile, denounced the “arbitrary” and “violent” detention Wednesday of Roberto de Jesús Guerra, who heads the independent news agency Hablemos Press in Havana.

Guerra was freed hours later, and on Thursday he reported that the government had just restored service to his cellular phone — the most efficient method of communicating on the island — after a two-month outage.

Hablemos Press writer Calixto Ramón Martínez was arrested in September and declared a hunger strike about three weeks ago to protest his continued detention.