Thousands of police officers are being mobilized to provide security for Friday's run of the Beijing Olympic torch through the streets of Argentina's capital, Buenos Aires.

Authorities say the extra forces include 1,500 naval policemen, at least 1,200 civilian policemen and 3,000 city workers. Officials want to avoid a repeat of anti-China demonstrations that disrupted relays in London, Paris and San Francisco.

The Olympic torch arrived in Buenos Aires Thursday after a flight from San Francisco, and was quickly taken to a secret location. Argentine football (soccer) legend Diego Maradona is scheduled to carry the torch at the opening of the relay.

In a separate development, U.N. Secretary-General Ban Ki-moon has informed Beijing it is unlikely he will attend August's opening ceremony. A spokeswoman says Mr. Ban informed officials months ago of a possible scheduling conflict.

The spokeswoman says the secretary-general is planning a "substantive visit" to China at another time.

World leaders are being pressured to skip the opening ceremony. British Prime Minister Gordon Brown, German Chancellor Angela Merkel and Poland's President Lech Kaczynski have said they will not attend the opening ceremony.

President Bush has also come under pressure from the top three U.S. presidential candidates to boycott the ceremony, but says his plans remain unchanged.

Meanwhile, the flame travels to Dar es Salaam in Tanzania on Sunday. Nobel laureate Wangari Maathai, who was to carry the torch, announced Thursday that she had pulled out, saying that she wanted to show solidarity with the people of Sudan, Tibet, and Burma.