China's worst earthquake in more than 30 years struck southwest China on May 12, leaving nearly 87,000 dead or missing.

The victims include at least 9,000 children who were crushed to death when their school buildings collapsed on them.

About 362,000 people were injured when the 7.9 magnitude quake struck southwestern Sichuan province and around 5 million people lost their homes.

Thousands of aftershocks and heavy rainfall compounded the difficulties for military, government and private workers trying to deliver aid and ensure people get shelter.

The government says the quake damage could exceed the devastating 1976 tremor in the northeastern city of Tangshan that killed up to 300,000 people.

Roads and phone lines in Sichuan were cut off by the quake, which caused buildings to sway as far away as the Thai capital Bangkok. The epicentre was in the mountainous county of Wenchuan, which has a population of about 100,000 people.

In the worst-hit areas - the hilly, rural area of Beichuan as well as Wenchuan to the southwest - buckled and blocked roads mean supplies and rescuers struggled to arrive. China mobilised 130,000 army and paramilitary troops to the area, some of them hiking in on foot.

Buildings toppled in at least six counties near the epicentre, Xinhua said. Anger has focused on the state of school buildings, many of which crumpled in the quake. The Housing Ministry has ordered an investigation. At least one hospital was also reported to have collapsed. In June the government ordered a nationwide safety inspection of all public buildings.

One of the most pressing needs is shelter. Soon after the earthquake, officials said 3 million tents would be needed. In May, state media said Premier Wen Jiabao had ordered 250,000 temporary housing units - simple steel structures normally used by construction workers - to the quake area by June 30. The was expected to reach 1 million within three months of the quake.

Officials are worried about possible damage to dams and the numbers of rivers that were blocked by landslides, forming more than 30 "quake lakes". Wen warned of the threat of "secondary disasters" caused by heavy rains and ordered experts to inspect dams and reservoirs on regular patrols.

Authorities evacuated about 250,000 people living downstream of the largest such lake, Tangjiashan. In June, floodwaters from the lake were released and swamped low-lying areas in the nearby wrecked town of Beichuan.

Immediately after the quake struck, China was put on precautionary alert against possible radiation leaks. The disaster area is home to China's chief nuclear weapons research lab in Mianyang, as well as several secretive atomic sites, but no nuclear power stations.

In May China said more than 25 billion yuan ($3.6 billion) in relief funds and donations from home and abroad had been contributed to the relief effort. Rescue teams from Russia, Japan, Taiwan, South Korea, the United States and Singapore have been helping search for survivors.

The U.S. Geological Survey said on its website that the main quake struck at 0628 GMT at a depth of 10 km (6 miles).

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