At least three people were killed after a 6.0-magnitude tremor hit the region early on Sunday.
While recovery efforts are switching to focus on clearing up the tonnes of debris left by the quake, a few survivors are still being pulled alive from the wreckage of collapsed buildings.
On Monday two women were pulled from the rubble of a collapsed coal mine in Beichuan county, one of the worst-hit regions.
A day earlier two men were pulled from the debris in the towns of Beichuan and Yingxiu, both in apparently good health.
Reports said at least 63 people were found alive across the region on Saturday.
State television reported that rescue crews in the quake-ravaged region had gone on heightened alert following the overnight aftershock, fearful further strong tremors could bring down already weakened buildings and cause more casualties.
"Rainfall and the aftershock have added difficulties to rescue efforts," it said, giving no details.
The region has experienced more than 20 aftershocks of magnitude 5.0 or above since the initial earthquake last Monday.
Al Jazeera's Tony Cheng, reporting from the hard-hit town of Dujiangyan, said that a week after the quake there was little indication from the authorities as to how they would handle the estimated 5 million left homeless.
He said entire cities across the quake zone had been decimated, and there was now an urgent need for long-term planning as survivors look to the task of rebuilding shattered communities.
China's revision of the earthquake's magnitude to 8.0 is likely to be noted by the superstitious.
Eight is a lucky number in China.
The Beijing Olympics are set to open on August 8, 2008 at 8:08pm.
Many on the internet have also commented that the earthquake itself took place exactly 88 days before the opening ceremony.
China on Sunday revised upwards the magnitude of the earthquake from 7.9 to 8.0.
Declaring three days of national mourning, officials also announced that the Olympic torch relay would be suspended for that period.
Beijing Olympic organisers said in a statement on Sunday that the suspension would "express our deep mourning to the victims of the earthquake".
The government is also ordering all flags be flown at half-staff and a halt to all public recreation activities.
The mourning period is the longest seen in China since the death of former leader Deng Xiaoping 11 years ago.
On Sunday the official People's Daily newspaper urged a nationwide "battle" against the disaster amid a rush by Chinese to volunteer for recovery efforts.
"More than ever, people are aware that to win the battle against the devastating earthquake requires the contribution of the whole country," the newspaper said in a commentary.
Flood threats from blocked rivers appeared to have eased, after three rivers overflowed without causing major problems, state media reported.
Xinhua quoted Liu Ning, engineer-in-chief with the ministry of water resources, as saying some facilities, such as reservoirs and hydroelectric stations, had been damaged but that no reservoirs burst.
Worries about possible flooding had earlier sent thousands of people fleeing the area.
More than 10,600 people are still listed as missing and thought to be buried in the remains of buildings in dozens of towns and cities across Sichuan, Xinhua said, citing regional officials.
Hu Jintao, the Chinese president, urged rescue teams to reach remote villages battered by the earthquake, according to Xinhua.
The number of security forces helping victims has risen to almost 150,000, while the government has pledged cash payments of $715 to each family that lost a member.
But some residents in the earthquake-hit areas complained the government was not doing enough.
|People continued to search for loved ones |
despite fresh aftershocks [Reuters]
The Associated Press said that one of its reporters was stopped at a petrol station in Miangyang city on Sunday by a group of about 15 people appealing for help for their village, Xiushui.
"The government is doing nothing to help us," said one man, handing over a note which said it had been signed "by the people of Xiushui".
More than 200 rescuers from Japan, Russia, South Korea and Singapore have been searching alongside Chinese soldiers.
The authorities, meanwhile, are also battling to prevent the outbreak of disease, with the risks heightened by the rotting carcasses of 12.5 million livestock and poultry.
"Combating epidemics is the most urgent and the biggest task facing us right now," Wei Chaoan, the vice-minister of agriculture, said on Saturday.
The World Health Organisation said that the lack of safe drinking water or proper waste disposal along with cramped conditions in temporary shelters was "conducive" to outbreaks.
"Preventing communicable disease outbreaks is the key public health issue now facing the People's Republic of China," the UN body said in a statement.