Chinese rescue workers are using explosives to clear mounds of rock blocking roads, as emergency teams try to reach isolated earthquake-hit towns in the south-western province of Sichuan.
The death toll in China's worst earthquake in three years stands at more than 200, with almost 12,000 people injured.
Firefighters, helped by sniffer dogs, have pulled 91 people alive from the rubble.
Rescue teams are queuing up and waiting to reach isolated towns, and some communities are still only accessible by helicopter.
Ongoing aftershocks are causing major landslides in the earthquake disaster zone, and falling rocks continue to block entry into some of the worst hit areas.
Chinese rescue workers with sniffer dogs were reported to have reached the most remote part of the region in Sichuan province hit by Saturday's
6.6 magnitude earthquake.
The rescuers had been travelling on foot because of damage to roads in the isolated region.
Communication networks were still disrupted, so the extent of the destruction was unclear.
China's Premier Li Keqiang is in Ya'an, the closest city to the epicentre, overseeing relief efforts.
More than 200 people are believed to have died and about 11,000 were injured.
The BBC reported that among the injured were 960 people who were seriously wounded.
While Chinese authorities do not expect the death toll to rise appreciably, much relief work needs to be done.
Soldiers worked all night to search villages and treat the injured, while local people slept in shelters or cars.
Premier Li Keqiang is overseeing relief efforts, and told reporters the rescue effort was "our first duty".
Mr Li, who arrived on Saturday afternoon by helicopter to direct rescue efforts, visited hospitals and tents, and climbed on a pile of rubble to view the devastation.
Villages close to the epicentre in Lushan county were left in ruins.
More than 13-hundred aftershocks have been felt in the area, raising fears of possible landslides.
Long traffic queues have also held up efforts to get aid supplies and volunteers to the affected areas and authorities have announced no new permits would be issued to journalists to travel to the region because their vehicles were adding to road congestion.
'New Zealanders know all too well'
Prime Minister John Key said New Zealand is offering technical assistance to China in the wake of the earthquake.
He said New Zealanders understand all too well the devastation caused by earthquakes.
Mr Key said he discussed general co-operation on disaster relief just last week, when he met Chinese Premier Li Keqiang.
Mr Key said New Zealand stands ready to offer technical support to China if help is requested following the latest disaster.