Zhang told officials to be vigilant in preventing any disruption of the torch's passage and said the journey could be a display of the region's stability.
"Tibet from top to bottom must keep a clear head at all times, without the least relaxation of our vigilance," he said. "Create a healthy social atmosphere of harmony and stability for the Beijing Olympic Games torch relay in the Tibet Autonomous Region."
On Friday, Xinhua said "an official was attacked and seriously wounded" in the riot in Sichuan.
"Police were forced to fire warning shots and put down the violence, since local officials and people were in great danger," Xinhua said in its English-language report, which was also carried in the China Daily on Saturday.
Chinese-language media did not carry news of the incident.
Ganzi and neighboring Aba in Sichuan province have seen angry confrontations between Tibetan protesters and police in the past weeks. Anti-riot troops have poured into the area.
Buddhist monks' protests against Chinese rule in Lhasa gave way to deadly rioting on March 14.
China says 19 people died in the Lhasa violence but representatives of the Dalai Lama say some 140 people died in the unrest across Tibet and nearby areas.
Sixteen mostly illiterate Tibetans were arrested on Saturday for a March 15 riot in which five people were killed in Dagze county about 25 km east of Lhasa, Xinhua said.
The dead appear to be five migrants from Henan province, burned in a motorcycle repair shop and included in China's official figure of 19 deaths, though Xinhua gave no details.
So far, 414 people have been detained for the March 14 riots in Lhasa, and 289 have turned themselves in voluntarily, Xinhua said. Six have been identified as "ringleaders," it said.
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