The Olympic torch arrived in Beijing last month amid tight security, and will pass through Tibet in June after completing an international tour. Chinese climbers will attempt to bring a separate torch to the peak of Mt Everest, on the Tibet-Nepal border, early in May.
Zhang warned officials to be vigilant against any disruptions of the torch 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 lead 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."
WARNING SHOTS
On Friday, China's state-run Xinhua news agency said that "an official was attacked and seriously wounded" in the riot in Sichuan, adding that "local officials exercised restraint" but did not give more details on the incident.
"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 neighbouring Aba in Sichuan province have seen torrid confrontation between Tibetan protesters and police in 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.
