Rock-throwing Tibetans are still defying a six-day crackdown that followed anti-Chinese protests in their capital, and the city will remain under martial law for at least another week, a Chinese official said Monday.

"Right now there is no possibility of the order being lifted," in Lhasa, said the official at the provincial office of Tibet in Beijing."Martial law in Lhasa will end only when the authorities are assured that the situation will stay calm."

He reported scattered cases of rock-throwing by Tibetans.

Tibetans contacted Thursday night after all foreign tourists had been expelled from the city reported large-scale roundups of Tibetans by Chinese security forces. It was not clear whether the reported mass arrests were continuing.

Chinese troops continued Monday to patrol Lhasa, which has been under martial law since midnight Tuesday, said the Chinese official, who spoke on condition of anonymity.

He said Tibetans defying the crackdown had been dealt with "harshly and in accordance with law."

In New Delhi, India, Monday, a total of 320 Tibetans staged sit-in protests in groups of four at 80 diplomatic missions, urging the nations to put pressure on China to lift martial law in Lhasa.

Police said they arrested 75 protesters and others escaped before they could be detained.