By JUAN O. TAMAYO
                      Herald Staff

                      HAVANA -

                      Some 15 to 20 Cubans who smashed a bus into the Mexican embassy in Havana
                      remained in the mission Thursday as President Fidel Castro, Mexico's foreign
                      minister and Castro foes blamed each other for the "provocation.''

                      Cuban police ringed the embassy and stepped up security around other diplomatic
                      missions amid rumors that they were accepting political asylum applications, but
                      witnesses reported overall calm in the Cuban capital.

                      Castro turned up at the scene shortly after the blue and white Mercedes bus plowed into
                      the embassy Wednesday, spending 20 minutes there and leaving after declaring, ''Tomorrow we must
                      get up early. There's work to be done,'' in an apparent attempt to turn down the tensions.

                      Witnesses said a man injured in the bus crash was later carried out of the embassy in a stretcher and
                      into an ambulance. Three other ambulances were reported to have sped off from the scene, sirens
                      blaring, but it was not clear if they were carrying more injured.

                      Police with batons and attack dogs and squads of pro-Castro civilians dressed in red T-shirts and
                      armed with wooden sticks and steel bars dispersed the crowds that gathered around the embassy,
                      witnesses said.

                      The Reuters news agency reported that policemen shouting ''Sons of Bitches'' hit two of its reporters.
                      It also said that state television officials prohibited Reuters Television from broadcasting images of the
                      incident to its foreign clients.

                      Havana residents said rumors that the Mexican embassy was accepting political asylum seekers began
                      swirling amid media reports of the comments in Miami Tuesday by Mexican Foreign Minister Jorge
                      Castañeda at the opening of a new Mexican cultural center.

                      Castañeda was quoted as saying that ''The doors of the embassy [of Mexico in Havana] are open to all
                      Cubans'' -- referring to human rights activists and dissidents long shunned by the mission under past
                      leftist Institutionalized Revolutionary Party (PRI) governments.

                      His comments were broadcast by several Spanish-language AM radio stations in Miami, whose
                      broadcasts reach Cuba, as well as the U.S. government's Radio Martí station, which broadcasts to
                      Cuba on short wave.

                      Small knots of Cubans began arriving Wednesday morning at the embassy in the once-tony Miramar
                      area in western Havana to ask about rumors that the mission was accepting asylum seekers, but were
                      told the rumors were false.