Adurahmin Mohammed Mahdi, a London-based spokesman for the Ogaden National Liberation Front (ONLF), said: "We handed them over to the ICRC."
"They are all very healthy. They are uninjured and very happy."
An ICRC spokesman in Addis Ababa confirmed the news and said the freed men were on their way to the regional capital.
"I can confirm that they have been released. They are on their way to Jijiga," the spokesman told reporters.
"I don't know if they have got there yet. They are all civilians."
Rights to self-determination
The ONLF have repeatedly warned investors they will not allow oil and gas exploration in Ogaden as long as local people were "denied their rights to self-determination".
The Chinese staff worked for Zhongyuan Petroleum Exploration Bureau, part of the much larger Sinopec, China's biggest refiner and petrochemicals producer.
Mahdi, the ONLF spokesman, said two Ethiopian men were also freed with the Chinese on Sunday after negotiations between the rebels' armed wing, ICRC officials and local Ogaden elders.
"It all went very smoothly," he said. "There was a ceasefire which we respected and the Ethiopians respected. The handover took place close to where the incident happened."
Liberty and freedom
He said the freed workers had been reassured the ONLF, which has been fighting for independence from Ethiopia since 1984, had nothing against the Chinese people.
"We never meant to take them as hostages," Mahdi said. "We removed them from the scene for their own safety. We are fighting for our own rights. So we would never deprive other people of their liberty and freedom."
The ONLF has blamed the deaths of the Chinese workers killed in Tuesday's attack on explosions caused by munitions during a fierce battle with Ethiopian troops guarding the facility.
Beijing had condemned the raid, which analysts said exposed the risks of its drive to use Africa's under-developed energy resources to feed a rapidly growing economy.
African governments have generally welcomed the Chinese push, which comes free of the political conditions often imposed by Western nations.
But there is concern in some quarters Beijing may be gaining too much control, treating local labour forces badly and flooding Africa with cheap, inferior goods.