The United States is condemning the prison terms being handed down to leading Cuban dissidents in what the State Department describes as "show trials" and "sham proceedings" by Fidel Castro's government.

The Bush administration has been watching the crackdown on Cuban dissidents with alarm and it is stepping up its criticism of the Castro government as the sentences in the closed-door trials which began late last week are being revealed.

Nearly 80 prominent human rights activists, independent journalists and other dissidents, rounded up by Cuban police last month, have faced summary trials in what the State Department Monday described as the "most egregious act of political repression" in the country in decades.

Among those sentenced were democratic reform campaigner Hector Palacios, given a 25-year prisoner term, and dissident journalist Raul Rivero and economist Marta Beatriz Roque, who were both ordered jailed for 20 years.

At a briefing here, State Department spokesman Philip Reeker condemned what he termed "show trials" of members of Cuban civil society. "The Castro government is persecuting journalists for acting like journalists. They're persecuting economists for acting like economists, and peaceful activists for seeking a solution to Cuba's growing political and economic crisis," said Mr. Reeker. "The regime's actions, we believe, are an appalling act of intimidation against those who seek freedom and democratic change in Cuba."

Mr. Reeker described as "very troubling" reports that prosecutors had asked for a death sentence for Jose Daniel Ferrer, a regional organizer in eastern Cuba of the "Varela Project," a democracy petition movement that drew international acclaim.

The Cuban activists are facing a variety of criminal charges including treason and subversion for allegedly collaborating with U.S. diplomats to undermine the country's economy and political system.

The crackdown, ending several years of relative tolerance by the Castro government, began last month when Cuban authorities lashed out at the head of the U.S. diplomatic interests section in Havana, James Cason, for actively supporting dissidents.

Spokesman Reeker, saying Cuba is further isolating itself in the hemisphere, called on Cuban authorities to release what he termed "these prisoners of conscience," end human rights abuses, and permit the exercise of fundamental freedoms.