U.S. Embassy diplomats who visited the site of clashes in Myanmar (search) between pro-government crowds and followers of a democracy leader saw bloody clothes and homemade weapons, suggesting far more people may have been killed than the four reported by the military junta, an Embassy official said Thursday.

The official said evidence gathered at the site also indicated the fighting in northern Myanmar, which broke out around democracy leader Aung San Suu Kyi's (search) motorcade as she toured the region last Friday, was orchestrated by the government. The junta detained her after the clash and has not disclosed her whereabouts.

"What they found corroborates eyewitness reports circulating of a premeditated ambush on Aung San Suu Kyi's motorcade," the official said on condition of anonymity.

The U.S. official said the two diplomats who visited the scene of the attack found signs of "great violence," including bloody clothing, numerous homemade weapons and smashed headlights and mirrors. The official would not detail all the information suggesting a premeditated attack but said it included photographs and physical evidence.

Myanmar's junta has said the fighting began when Suu Kyi's motorcade drove through a crowd of townspeople protesting her visit and that four people were killed. Exile groups allege that government-backed forces staged an ambush and that 70 or more people may have been killed over two days.

At least 19 members of Suu Kyi's National League for Democracy (search) party were also detained. The military, which has put Suu Kyi under house arrest several times since 1989, has repeatedly sought to quash her movement and said she was taken into "protective custody."

Exile opposition groups have also claimed that Suu Kyi, winner of the Nobel Peace Prize (search), was hurt in the violence, perhaps suffering severe head injuries. The junta insists that Suu Kyi and colleagues detained with her are fine — although it refuses to divulge where they are held.

Tight media controls and the remote location of the clash made it impossible to confirm what happened. Phone lines to the area appear to have been cut.

Myanmar's government is under pressure to produce Suu Kyi by Friday, when U.N. special envoy Razali Ismail (search) is planning to visit. Razali told The Associated Press in Kuala Lumpur he expected to meet junta leader Gen. Than Shwe to push for Suu Kyi's release.

"Suu Kyi must be released," he said.

In late 2000, Razali brokered reconciliation talks between the government and Suu Kyi, whose party won 1990 general elections but was blocked by the military from taking power. The talks had provided hope that the country's political impasse could be bridged, but the dialogue reached a standstill last year.

Razali said senior U.N. officials had asked him to proceed with the visit even though the junta has refused to give assurances that he would be allowed to meet her.

"They feel that I should go, that the trip should take place and that I should express the U.N. strong stand to the Myanmar government that Suu Kyi should be released and that I should be allowed to see her," he said.

A United Nations official in Yangon said on condition of anonymity that "if Razali is not allowed to see her, that will only strengthen the rumors about Suu Kyi being hurt."

The International Committee of the Red Cross (search) has also asked to see Suu Kyi and colleagues believed detained with her — among them the vice-chairman of her party, Tin Oo (search).

Western countries, including the United States, have demanded the release of Suu Kyi and leaders of her party. Her party's offices have been closed across the country.

Even some of Myanmar's Asian neighbors who usually avoid criticizing the regime have expressed dismay over the arrest.

Suu Kyi won the Nobel Peace Prize in 1991 for her nonviolent struggle to promote democracy.