After days of refusing foreign relief workers, China accepted offers from four countries to send in rescue teams, as the search for those trapped by the earthquake reaches a critical stage.Hours after saying it will accept a Japanese rescue team, the Foreign Ministry said in a statement early Friday that specialist crews from Russia, South Korea, and Singapore would be welcome as well.The turnabout comes as the death toll from Monday's magnitude-7.9 quake jumped to nearly 20,000 and the government said the number could more than double to 50,000.Rescue work has reached a critical stage as chances for survival for those trapped fall after 72 hours and the government has vowed not to abandon the search for survivors.The communist government has for decades refused outside expertise in disaster relief operations, preferring to rely on massive military mobilisations. After Monday's quake pulverised vast areas of Sichuan province, the government initially said it welcomed foreign aid, money and goods but not international rescue workers.The Japanese team is made up of firefighters, police, technicians and medical and other personnel, personnel, and half its 61 members arrived in the Sichuan capital of Chengdu early Friday.A 29-member Russian team, including rescuers and medical staff, planned to leave from Russia Thursday on its way to affected areas to help with searching for survivors and clearing rubble, the Xinhua News Agency said.It was not clear when the South Korean team would arrive. Korea has 41 rescue workers and more than 20 medical staff on standby, according to Yonhap News Agency.China had so far received international aid worth more than $US100 million ($A107.24 million) and materials worth more than US$10 million, Foreign Ministry spokesman Qin Gang said at a routine media briefing Thursday. But it still needed supplies of tents, clothes, communication equipment, machines for disaster relief, and medicines, he said.At the time, Qin did not commit to receiving further assistance from foreign countries. He said China was thankful for offers from foreign countries and organisations but was studying proposals for more rescue teams according to the progress of the rescue work and actual situation on the ground and the receiving capability.Some relief organisations and foreign governments said they offered assistance earlier this week only to be turned down. An Australian offer to send expert search and rescue teams has yet to be accepted, an Australian aid official said on condition of anonymity because she was not authorised to speak the media."The Chinese authorities have done a fantastic job mobilising troops, but troops are not everything. You need specialist teams with equipment, otherwise you're not going to find them," said John Holland, operations director of Rapid UK, a British-based search and rescue charity whose own offer was turned down earlier this week.Vice Governor Li Chengyun of Sichuan province told reporters Thursday that China had not asked for outside help."Chinese people and the government have the ability to deal with this type of disaster," he said.AP