Chinese troops killed scores of Tibetans by firing at random on crowds during three days of unrest, Tibetans told foreign travelers Thursday, urging them to "tell the world . . . help us, please."

China, meanwhile, said Tibetan separatists living abroad had smuggled weapons into the disputed southern region and instigated the riots.Chinese authorities expelled about 40 foreigners from the Tibetan capital of Lhasa Thursday as troops enforced martial law and isolated the embattled city.

Tourists ordered out of Lhasa said Tibetans feared there would be reprisals once all foreigners were expelled.

"People begged us repeatedly over the last few days - `tell the world, help us please,' " said an American from New Orleans, speaking on condition of anonymity.

"They grab your hand and say, `help us,' and they cry," said a West German woman.

China on Tuesday declared martial law in the city of 70,000 following three days of rioting in which 12 people were killed and more than 100 injured by official count. Tibetans say far more died.

All foreign visitors, estimated at about 140, were ordered to leave by Thursday. One group that flew to Chengdum, the capital of neighboring Sichuan province, issued a statement they said would be sent to the United Nations and to Tibet's exiled spiritual leader, the Dalai Lama.

"It is our urgent and heartfelt wish that the world community should carefully and critically examine the causes of this conflict and the methods and motives of the authorities," the statement read.

"While the Tibetan demonstrators became violent and destructive in expressing their anger and frustration, we feel that the magnitude and bloodiness of the crisis has been caused by the incompetence of the authorities.

"Shootings by the authorities have been excessive, unpredictable, indiscriminate and there have on occasion been atrocities," it said.

China Thursday also announced that all foreigners in Lhasa must report to the police, that Tibetans harboring criminals must turn them in and that police will continue to search for separatists.