China's civil aviation authority issued a circular on Thursday urging domestic airlines to strengthen risk assessments and secure flight safety.

The move followed the crash of a Russian airliner, in which 170 people died, in eastern Ukraine on Tuesday.

With speculation that the accident was caused by bad weather, the Civil Aviation Administration of China required air traffic control departments to closely monitor weather changes and provide accurate forecasts.

"Fickle weather and the current brisk traffic have compounded the difficulties of safe flight," said the circular.

The administration also ordered an immediate survey of the navigability of all aircraft, especially those with long service.

"Airlines must strengthen control of ground services at airports within their jurisdiction and pay special attention to the navigability of their aircraft at other airports," said the circular, stressing the necessity of "eliminating hidden dangers before aircraft take off".

The administration also prohibited overtime for flight crews, requiring pilots and stewards to strictly abide by flight schedules.

Airlines violating the rules would be penalized, it said.

(Xinhua News Agency August 25, 2006)