The men were said to have been buried alive by mounds of rock and clay as they were quarrying stone for the site at the foot of a hill in Tuong Duong district in Nghe An at 10am local time (0300 GMT) on Friday.
"Authorities are using machines trying to search for them, but their chances of survival are almost none," police officer Dinh Ngoc Sang told AP news agency.
Officials said explosives had earlier been used at the mine to help remove the stones from the mountain.
However they could could not confirm whether this caused the accident.
Rescue workers said it could take weeks to remove the rocks to get to the bodies and none had been found so far.
Nguyen Tan Dung, the Vietnamese prime minister, sent condolences to families of the victims and has ordered an inquiry into the cause of accident, state television network VTV reported.
Hoang Trung Hai, Vietnam's deputy prime minister, was sent to the province to oversee the search operation, the network said.
Güncelleme Tarihi: 15 Aralık 2007, 18:20