At first the gash of freshly turned earth looks like one of the hundreds of landslides triggered by China's massive earthquake. But the incense sticks and half-burnt candles along the road hint at a hidden purpose.

The scar on the hillside has become a mass grave for the victims of the disaster. A line of young soldiers, their faces covered by blue masks against the stench of decomposing bodies, stand guard. More troops, their uniforms protected by blue plastic coats, squat at the foot of the slope, waiting for the next grim delivery.

“The authorities asked us to bury them quickly because they have been dead for several days. There is no time to wait. It's already been quite a long time and now the weather is starting to get warmer,” an official said.

A digger had be2en brought in to cut a path up the hill and carve out three trenches, each about 50 metres (160ft) long and more than 1.5 metres deep. One trench had already been filled.

Officials refused to say how many bodies had been buried or how many they expected to receive. “How many will be buried here we don't know yet,” one said. They hope to ensure the health of the living while respecting the dead.

The site chosen for the grave is a disused lime kiln on the edge of Libin village. It stands at the foot of the line of jagged hills in which tens of thousands have died around the epicentre of the tremor that shook China on Monday. Yesterday the offical toll was raised to 22,069. A further 14,000 were missing in Sichuan province, which bore the brunt of the quake.

An army officer explained that the soldiers' task was to line the grave with lime and then lay in the bodies. More lime was then thrown over and it was sprayed with disinfectant. But the officer hoped that it would not be an anonymous grave and that one day the bodies could be claimed by relatives - if any have survived.

A photograph was taken of each body. Hair and blood samples were recorded to enable DNA identification later. Mortuaries and hospitals in the area are already overwhelmed. In some areas there is insufficient electricity to provide power to keep the bodies. There is no option but a swift burial, with as much dignity as possible, in a land plunged into grief.

A doctor speaking on the special radio channel devoted to the disaster explained the need to dispose of the bodies as quickly as possible. The site should be well away from water sources, and bodies should be disinfected and buried with lime to prevent the spread of disease.

The soldiers working at the mass grave, a handful from the more than 130,000 People's Liberation Army troops deployed, were nervous.

They were under orders to keep away anyone trying to pry as the bodies were brought in. One young man who had been deployed from the air force in the central city of Wuhan, said: “It's dangerous here. And we are very busy. No one can come in.”

A young farmer working nearby shrugged when asked if he was afraid to have such a large grave on a hillside so close to his home. “What is the point of being frightened? They have to be buried somewhere after all, and there are so many of them.”

Thousands more bodies are believed to be still lying entombed in the ruins of their homes and schools, offices and factories. But amid the tragedy there are still glimmers of hope.

Exactly 100 hours after the massive earthquake at 2.28pm on Monday, cheering soldiers pulled a survivor from the wreckage of a fertiliser plant in Yunhua.

Liu Deyun should not even have been in the Yinfeng Fertiliser Plant when the earthquake struck: the 50-year-old driver had been due to make just a quick delivery. But when the building crumpled he was chatting in the games room.

His incredible rescue, witnessed by The Times, began when an army medical team picking through the ruins on Thursday afternoon heard sounds of life. To their amazement, they were able to speak to the trapped driver.

His daughter, Liu Yuanyuan, had gone to search for him a day earlier but was told not to bother and to go home. She returned when she heard that survivors had been found.

“I talked to my father. I called out: 'Daddy' and he wept and said: 'I want water'. I told him not to talk and to preserve his strength for the rescue. He said that he could not move at all.”

His body was pinned down by such huge concrete slabs that doctors had to amputate a part of one leg to free him.

A military doctor, Zhao Hongxiu, said: “We discussed with him that we would have to operate. He agreed that the most important thing was to save his life.” Workers at the plant said they feared that more than 200 people were buried in the rubble. Soldiers sprayed disinfectant over the debris to cover the stench of rotting bodies.

Even as soldiers cheered at the rescue of Mr Liu, rescue teams were burrowing into the other side of the building. Three men who had been playing mahjong together were still alive.

Times Recommends

• Google to digitise Iraqi artefacts
• Renault angers parents by naming new car Zoé
• Analysis: most lawless part of Philippines