Foreign rescue teams arrived in China's quake-devastated southwest on Friday, laden with specialist equipment to aid the desperate search among the rubble of shattered buildings.

A Japanese team began work in Sichuan province, the first time the Chinese government has accepted foreign professionals for a domestic disaster rescue and relief operation.

But experts warned that time was running out, as one British search and rescue team struggled to get permission to enter China from Hong Kong.

A team of 31 Japanese rescuers, accompanied by sniffer dogs, arrived Friday in the town of Guanzhuang of Qingchuan county, an isolated area near the mountainous border with Gansu province where 700 people are believed buried.

"We want to do our best to rescue as many people as possible," a member of the rescue team, wearing an orange-and-blue worksuit, told Japan's TV Asahi network when they arrived in Sichuan.

Japanese television showed footage of the group arriving later in Qingchuan and holding talks with their Chinese counterparts on how to divide up the work.

A second batch of 29 emergency firefighters, police and coastguard workers left Japan for China on Friday.

"Needless to say, time is running out. We want to speed up our efforts to save people's lives with cooperation with the Chinese side," a foreign ministry official said in Tokyo.

Teams from South Korea, Singapore and Russia have also been granted access to the region, alongside teams from Hong Kong and separately-governed Taiwan, which China still considers part of its territory.

The 41 rescuers from South Korea's National Emergency Management Agency left Seoul on Friday, along with two sniffer dogs and "state-of-the-art" search technology.

Their equipment includes digital endoscope cameras which can be inserted into building cracks to seek out any survivors, the agency said in a statement.

The Singapore team brought along life detector systems and hydraulic cutters and spreaders, it said.

The decision to accept the rescuers signals an apparent shift by Beijing, which initially had politely rebuffed such offers despite clearly struggling to reach many devastated communities cut off by quake-damaged roads.

In previous disasters, such as the Tangshan earthquake of 1976 which killed more than 240,000 people, China even refused offers of aid from abroad, insisting the money was more needed elsewhere.

Despite the unprecedented access, 10 members of British-based International Rescue Corps were still in Hong Kong Friday trying to secure permission to enter the mainland.

"Realistically, we are now on day five and you have to ask how long people can survive," the charity's director Willie McMartin told AFP, when asked if they would still enter China if they faced further delays.

McMartin said the 10-member team, who had arrived to Hong Kong Wednesday night, were hoping to get a flight at 7:00 pm (1100 GMT) on Friday to Sichuan's capital Chengdu, and would reassess the situation if permission had not been granted by then.

He said British embassy officials in Beijing were helping to try to secure visas from Chinese authorities.