From staff and wire reports

                  HAVANA (CNN) -- Cuban President Fidel Castro, who hosts next week's
                  Ibero-American Summit in Havana, has sent a tough warning to dissidents
                  organizing protests around the event -- including a foiled opposition march.

                  "Nobody has impunity at the moment, nor at any moment," he said, banging
                  his fist on the table during a marathon eight-hour meeting with reporters that
                  ended early Thursday. "We cannot allow ourselves to be tolerant with them."

                  Castro said two men were arrested and would be charged with provoking
                  social disorder after Wednesday's disturbance in a Havana park. Students
                  and government supporters angrily confronted the pair as they unfurled protest
                  banners and spoke to reporters.

                  The planned opposition march did not take place.

                  Castro: Supporters spontaneously attacked dissidents

                  Castro said government supporters who attacked the would-be marchers
                  were reacting spontaneously to provocation by Cuba's enemies.

                  "They have suffered under the blockade. They have suffered," he said. "They
                  became irritated by those people who help our adversary. It's logical."

                  Castro's comments were the latest in an offensive by Havana against Cuban
                  dissidents who for weeks have been organizing activities such as news
                  conferences and meetings ahead of the summit of leaders from Latin
                  America, Spain and Portugal on Monday and Tuesday.

                  The summit is the most important event for Cuba since Pope John Paul II's
                  historic visit in January 1998.

                  Dissidents ask summit attendees to hear their cause

                  Cuban dissidents, who belong to many tiny and often divided groups, insist
                  they represent peaceful opposition to Castro's one-party socialist system.

                  They are urging Ibero-American leaders to back their cause, or at least listen
                  to them, during next week's summit.

                  Some Ibero-American leaders, including those from Spain and Portugal,
                  have scheduled meetings with dissidents in Havana.

                 Castro warns against demonstrations during summit

                 Dissidents still are planning a gathering Friday of dozens of opposition
                 groups. But Castro sternly warned against any demonstrations during the
                 summit.

                 "If there is someone who breaks the law, our authorities will not hesitate to
                  arrest them and submit them to trial so that they receive appropriate
                  sanctions," he said.

                  Castro brought before reporters a group of people whom he said witnessed
                  Wednesday's confrontation. They said the confrontation represented an
                  unplanned show of support for the 1959 revolution that brought Castro to
                  power.

                  "This is an ideological war; we have to defend our ideas," said Nancy
                  Wilson, head of a construction crew that clashed with the dissidents.

                  The Cuban president showed what he said were banners raised by
                  dissidents, and accused the protesters of being paid by U.S.-based activists.

                  He read out what he said were criminal records of the two men arrested, in
                  an attempt to prove that Cuba's small internal opposition consisted of petty
                  criminals encouraged to agitate by U.S. officials and groups.

                  "They have created a sort of profession to be a dissident," Castro said,
                  adding that the U.S. diplomatic mission in Cuba -- the Interests' Section
                  attached to the Swiss Embassy -- was responsible.

                  Castro said that if security officials had not restrained the public anger
                  against the two protesters, the incident could have been worse because of
                  the messages on dissidents' placards. One read, "Justice for murdered
                  children," the other, "We demand human rights.

                  Dissidents claim attackers were security forces

                  Dissidents who were kept from marching on Wednesday said their
                  attackers were government security forces dressed as civilians.

                  The protesters had hoped to demonstrate for human rights,
                  democracy and the release of political prisoners.

                  "One of the biggest waves of political oppression in recent years is taking
                  place," Elizardo Sanchez, head of the nongovernment Cuban Commission
                  for Human Rights, said in a statement.

                  He condemned "the disproportion between such actions and the absolutely
                  peaceful nature of the opposition activities."

                  The rights commission said 40 dissidents had been arrested since November
                  1, with 20 still being held on Thursday and 18 others confined to their
                  homes.

                  Castro also denied U.S. President Bill Clinton's charge last week that the
                  Cuban government had sabotaged efforts to improve U.S.- Cuba relations.

                  "I was surprised by the lack of ethics in those pronouncements, the
                  falsehood of the statements," Castro said.

                  He said he believes Clinton sincerely wants to improve relations with Cuba
                  -- but personal weakness stops him.

                  "Clinton, in my judgment, has a defect. He gives in too quickly to pressure,"
                  he said.

                    Reporter Frida Ghitis, The Associated Press and Reuters contributed to this report.