UN chief Ban Ki-moon will on Saturday visit China's earthquake zone, the government said, as it warned rebuilding the area where more than 55,000 died would take years.

Ban will visit a small village in the remote mountains of Sichuan province, which was at the epicentre of the May 12 quake and was almost completely flattened, the Chinese foreign ministry said Friday.

Ban will have travelled from one disaster zone to another after spending two days in neighbouring Myanmar, where he pressed the ruling military to speed up efforts to help victims of the horrendous May 2-3 cyclone.

The announcement of Ban's visit came shortly after China raised the confirmed quake death toll to 55,740, a rise of 4,500 from the day before, with another 24,960 people missing.

Chinese officials also warned of rising disease dangers for the millions of survivors and that rebuilding the quake-ravaged areas would take at least three years.

But there was some positive news with another dramatic survival story, this time of an elderly couple who had been stranded for 11 days.

More than 5.47 million people were left homeless in southwestern Sichuan province -- or around one in five in the affected area that is the size of South Korea -- with most now crammed into overflowing tents or stuck outside.

"Now is the peak season for disease outbreaks and the situation is extremely grim," Sichuan Vice Governor Li Chengyun told a news conference in Beijing.

He said people badly needed tents and medical supplies, especially antibiotics, although he noted no outbreaks of disease had yet been reported.

China has made a global appeal for 3.3 million tents and ordered the construction within three months of one million simple homes made of light materials.

But Li warned it would take much longer to rebuild communities, not to mention addressing the lasting psychological scars inflicted by an earthquake so powerful it was felt in Bangkok.

"We aim to improve roads and infrastructure and build new villages, towns and cities within three years," the vice governor said.

"The mountains were basically shaken loose by the earthquake, causing mud flows and landslides, making reconstruction much more difficult than the work before the earthquake."

In the hills above Dujiangyan, about 50 kilometres (32 miles) from the quake's epicentre, people were working overtime to build pre-fabricated homes.

"We need tents and shelter," said Song Guosu, 58, one of more than 100 people waiting in rudimentary shelters as bulldozers moved across a muddy field nearby to clear land for makeshift housing.

Officials said the government's top priority was rescuing anyone trapped under the rubble 11 days after the quake.

No one has been rescued from under the debris since Tuesday, although the state-run Xinhua news agency reported another improbable story of survival.

An elderly couple, aged 92 and 84, had been trapped in their cottage on a mountaintop in a village near the top of Mount Qingcheng, a summit in Sichuan that is revered in the Taoist faith.

A police team found the couple, Tian Yueqing and Cao Shuyun, on Thursday, and carried them to the foot of the mountain on stretchers, Xinhua said.

Such rescue stories have inspired the Chinese public, who this week observed an unprecedented three days of national mourning for the tragedy.

The Beijing Olympic torch, which has been greeted enthusiastically across China after a protest-marred international leg, arrived Friday in the bustling financial hub Shanghai, but the mood was sombre.

"We are here to support China," said Ren Fufu, a retiree attending the opening ceremony.

"The torch must continue its journey because it shows our solidarity with the earthquake victims and the Beijing Olympics are a world event," she said.

To raise 13 billion-dollars for relief and reconstruction work, the government this week ordered five percent cuts to this year's national budget.

People from within China and abroad have also responded to the call for financial help, with 24.6 billion yuan (3.5 billion dollars) collected in donations for relief and rescue work, the government said Friday.

Authorities are also focusing on helping non-human victims. Six rare giant pandas were evacuated from the famed Wolong breeding centre due to food shortages and damage from the earthquake.