Urumqi, capital of northwest China's Xinjiang Uygur Autonomous Region, has been enveloped in heavy fog for 55 hours, the longest in 30 years, local meteorology bureau said here Thursday.

Only the top floors of the 39-storey Bank of China building in Urumqi are visible in thick fog Thursday. The capital of nrthwest China's Xinjiang Uygur Autonomous Region has been shrouded in fog since Tuesday, the longest period in three decades, according to the regional meteorological station.

Dense fog rose on Monday morning and persisted until 5 PM Wednesday. The fog dispersed Wednesday evening but rose again during the daytime Thursday.

The local meteorology bureau issued an orange alert, the highest level alert, on Wednesday. The lowest temperature fell to minus 11.1 centigrade.

Previous records show that the most persistent fog lasted 44 hours thirty years ago.

(Xinhua News Agency, China Daily, November 25, 2005)