China's vice-premier Hui Liangyu said on Tuesday the toll in the May 12 earthquake in the southwestern part of the country may go well beyond 80,000.

Hui's statement was the first official acknowledgement that many of those still listed as missing most likely perished.

"The May 12 earthquake in Wenchuan county was the most destructive earthquake, one that affected the widest area and posing the biggest challenge to rescue operations, since the founding of the People's Republic of China (in 1949),” he said.

He admitted that the relief work has been arduous.

Hui said the earthquake affected 417 counties, 4,656 townships and 47,789 villages, over a total disaster zone of 440,000 square km. The number of people affected was 46.24 million.

He said the relief work was difficult because most of the worst hit areas were in the mountains or deep valleys. The destruction of roads and communication links also prevented rescue staff and facilities from getting into the quake zone quickly.

He said 7.79 million houses collapsed, with another 24.59 million damaged. The county seats of Wenchuan and Yingxiu Township were almost levelled, he noted.

Infrastructure was also severely damaged. The quake cut off 16 major arteries and six railways and paralyzed power supply, telecommunications, and water supply in large areas, he said.

Secondary disasters caused further damage, with landslides and mud-rock flows frequently striking the zone, Hui said.

Quake-triggered landslides blocked rivers and formed 35 quake lakes, with dangers of various degrees reported in 2,473 reservoirs.