At least four opposition leaders were arrested Wednesday in Havana during showy police raids, sources in Cuba told The Herald.

Vladimiro Roca Antunez, president of the Social Democratic Party, and Marta Beatriz Roque Cabello, director of the Cuban Institute of Independent Economists, were arrested at their homes.

Felix Bonne Carcaces, president of Cuban Civic Mainstream, and Rene Gomez Manzano, president of the independent lawyers group Agramontist Mainstream, are believed to be under arrest, the sources said. The group is named after Ignacio Agramonte, a lawyer who died in 1871 during Cuba's war of independence from Spain.

The four detainees are members of the Domestic Dissidence Working Group and had arranged to meet Wednesday morning at Roque's home.

Chuny Montaner, the Working Group's representative in Miami, confirmed that Roca and Roque were arrested at their respective homes.

Quoting witnesses who requested anonymity, Montaner said Cuban police arrived at Roca's home, in Havana's Nuevo Vedado section, about 8 a.m. and conducted a four-hour search of the premises.

At about 9 a.m., police burst into Roque's home, in the Santo Suarez section, and took her away, along with eight other people, Montaner said. The witnesses told her they were unable to identify the others.

The reason for the arrests is unclear, although sources on the island said it might be related to the Working Group's two recent press conferences for foreign journalists.

The group's June 27 press conference in Havana was transmitted by telephone to Washington and Miami. At the time, the dissidents made public a document titled The Homeland Belongs to Everyone, which they wrote in response to the draft manifesto of the Fifth Congress of the Cuban Communist Party, to be held in October.

Ricardo Bofill, president of the Cuban Committee for Human Rights, said Wednesday in Miami that the Working Group has become such an important center for political activity that the government of President Fidel Castro probably sees it as a threat.

``In recent months, this group managed to revive the internal political activism that waned after the crackdown on Concilio Cubano in 1996,'' Bofill said.