The CODECO militia attacked a Chinese-managed mining site in Mungbwalu village, Ituri province, overnight on Wednesday, army spokesman Lieutenant Jules Ngongo told AFP.
Militiamen killed three miners in the attack and kidnapped four Chinese workers. But the army staged a counter-attack and managed to free two of the captives, Ngongo said.
"We lost a soldier, who succumbed to his wounds," he added.
Innocent Madukadala, the chief of a group of villages in the Mungbwalu area, confirmed that the army had freed two Chinese men.
The status of the missing two Chinese is unclear, however.
Armed groups often fight for control of mines in gold-rich Ituri, which has been plagued by militia violence for years.
Attacks on Chinese-managed mines in the Democratic Republic of Congo also appear to have increased of late. Two Chinese nationals were killed in a mine attack in Ituri in November.
The CODECO -- the name for the Cooperative for the Development of the Congo -- is a political-religious sect that claims to represent the interests of the Lendu ethnic group.
It is considered one of the deadliest of over 120 militias operating in the eastern DRC, blamed for a number of ethnic massacres in Ituri.
Last year, the Congolese government placed security officials in charge of the administration of Ituri and neighboring North Kivu province in a bid to curb violence.
The measure has failed to stop attacks.
CODECO Hits DRC Mine
FILE: Employees stand in an open pit at Banro's Twangiza mine in eastern DRC's province of South Kivu where rebel groups operate. Taken 9.28.2011
Four people have been killed and two Chinese workers gone missing after soldiers and militiamen battled over a mine in troubled eastern DRC, the army said on Friday.
BUNIA, DRC —