(For related story see QUAKE or [ID:nPEK277913])

May 15 (Reuters) - Tens of thousands of troops, firefighters and civilians are racing to save 25,000 people believed to be buried in towns across southwest Sichuan province, where the death toll may rise to 50,000.

The 7.9-magnitude quake that struck on Monday is the deadliest since a 1976 quake in the city of Tangshan, near Beijing, which killed up to 300,000 people.

Here are five facts about relief efforts.

* China's military is leading disaster relief efforts. More than 150 transport planes and helicopters are parachuting in troops and food, medicines and tents. Hundreds of troops are heading for remote towns on foot. The deployment is China's largest ever non-combat air operation.

* The huge number of victims and the problem of accessing remote regions where connecting roads were severely damaged are the two major difficulties facing rescuers. People trapped under rubble could survive for up to a week, Wang Zhenyao, Director of the Disaster Relief Department of the Ministry of Civil Affairs, said on Tuesday.

* About 100,000 soldiers, armed police and paramilitary personnel are expected to be involved in the search for survivors. More than 47,800 have already been sent to affected areas. Another 30,000 will join them and the 16,000 policemen already involved, military sources said.

* Thunderstorms and heavy rain on Tuesday prevented air operations in Wenchuan county -- the quake epicentre and one of 44 severely affected counties and districts in the province. By Wednesday night, Chengdu Military Area Command had helicoptered in 33.3 tonnes of food, drinking water and medicine, and helicoptered out more than 150 injured, Xinhua news agency said.

* The central government has allocated 1.1 billion yuan ($157 million) for quake-hit areas; the public has donated 877 million yuan ($125 million) in cash and goods. A Japanese relief team which set off for China on Thursday will be the first foreign team to travel to the disaster zone. Self-ruled Taiwan, which China considers its own territory, is offering T$2 billion ($71 million) in aid, and its public has raised another T$2.2 billion. Sources: Reuters, Xinhua (Writing by Gillian Murdoch, Beijing Editorial Reference Unit; Editing by Nick Macfie)

AlertNet news is provided by