LHASA, Dec. 19 (Xinhua) -- The Potala Palace, a World Heritage site in Lhasa, China's Tibet Autonomous Region, announced an unscheduled closure Wednesday after 24-hour snow battered the regional capital city.

Due to the heavy snow, the steep stone stairs leading to the Potala Palace atop a hill became slippery, according to a statement released by the palace's administrative office late Tuesday.

"The palace is usually only d on the Tibetan New Year's Eve and the second day of the New Year. There was no closure due to weather in the past," said Jorden, deputy director of the palace administrative office.

Over 440 palace staff and some 30 firefighters participated in the snow removal Wednesday, according to Jorden.

This winter's first snow in Lhasa came early Tuesday morning and did not stop until Wednesday morning. The city saw 10 cm of snow, and the temperature dropped to minus 9.4 degrees Celsius at 9 a.m. Wednesday, according to the regional meteorological bureau.

The snow was about 52 days later than when it usually came in other years, said Du Jun, director of the regional meteorological center.

The regional meteorological bureau issued a yellow alert for a blizzard Tuesday morning.

The Potala Palace was built by Tibetan King Songtsa Gambo in the seventh century and was expanded in the 17th century, covering an area of 41 hectares atop a craggy hill in the heart of Lhasa.

As one of China's top tourist destinations, the palace was included on the UNESCO World Heritage List in 1994. It received 1.45 million tourists in 2017.