LONGTOUSHAN, China - China called for volunteers to stay away from an earthquake disaster zone Wednesday as traffic blocked supply routes and "substandard" relief goods flooded into the area.
Rescue efforts in the southwestern province of Yunnan, where at least 410 people died in Sunday's 6.1-magnitude quake, have also been hampered by landslides blocking roads.
In Longtoushan, the quake's epicentre, workers halted traffic as they set off explosions on the mountainsides to dislodge huge boulders perched precariously over roads.
Huge tailbacks have developed around the worst hit areas, mainly consisting of cars driven by members of the public bringing in supplies or offering help.
Pang Chenmin, head of the ministry's disaster relief bureau, urged the public to avoid the disaster zone as the 72 hour "golden period" for rescue drew to a close.
"In order to ensure the best chances of rescuing survivors, we advise non-professional groups and volunteers against entering the quake zone by themselves so as not to cause traffic and communication difficulties," he said, according to the official news agency Xinhua.
Many volunteers who walked or hitchhiked to Longtoushan have slept out in the open, or entered tents used by survivors.
Some brought their own vehicles into the worst-hit areas, carrying in goods such as fizzy drinks.
"Some relief materials are unfit for use in disaster areas, some are substandard products, some are overly abundant and take up precious space and traffic resources," added Pang.
A huge tremor in Sichuan in 2008 which killed more than 80,000 people - China's worst quake since 1976 - sparked a wave of public sympathy and a huge volunteer rescue effort.
Subsequent earthquakes have seen problems with volunteers, who have sometimes been labelled "disaster gawkers" by Chinese media.
Search efforts in Longtoushan were being concentrated in a 600-metre swathe of hillside in the township's central urban area.
The body of a young child was pulled out in front of relatives wailing in grief late Tuesday night.
More than 18,000 professional rescuers have headed to the disaster zone, state media said, most of them military and police.