NANNING, Feb. 5  -- South China's Guangxi Zhuang Autonomous Region has ordered local transport companies to monitor vehicles in use around the clock following a weekend coach crash that left 13 people dead.

Transport companies must track vehicles, especially those on long-distance journeys, by global positioning systems and report to the traffic management authorities on a daily basis, said Chen Hongqi, head of the regional work safety supervision administration.

"On long-distance journeys, companies must arrange at least two drivers on each vehicle and they must work in shifts," said Chen.

In addition, road management companies in Guangxi have been ordered to set up more warning signs near accident black spots and to strengthen vehicle safety tests.

Two coaches, one carrying 41 people and the other 48, collided on a highway in the Yao Autonomous County of Du'an, in Hechi City, on Saturday, the first day of the national 40-day Spring Festival travel season.

Eleven people died at the scene and two others died in hospital.

Fifty people were injured, including four seriously. All the injured are described as stable.

Local authorities are investigating the accident.