The ELN, as Colombia's second biggest guerrilla group is known, did not mention a Canadian seized at the same time.
Colombian military and police sources could not immediately confirm the release of the five captives.
The men, all of whom worked at the Snow mine project belonging to Canada's Braeval, were freed after being told the charges against them, the rebel group said in a statement.
The ELN is also holding two Germans believed to be retirees who were travelling as tourists in Colombia.
The rebels have asked for proof that the men are not intelligence agents.
The mine workers' kidnapping demonstrates that although security in the Andean nation has improved in recent years, there are still great risks for people in remote mountain and jungle areas.
The kidnapping of foreigners, including oil workers and tourists, had been a common method of pressuring the government over the past decade and of keeping people from venturing into rebel-controlled areas.
Military pressure and widespread anger among Colombians and in the international community seemed to slow the trend until recently.
It is not known how many foreigners remain in rebel camps.
Considered a terrorist group by the US and the EU, the ELN is not included in negotiations under way in Cuba between the Colombian government and the nation's biggest insurgent group Farc, or the Revolutionary Armed Forces of Colombia, to bring an end to five decades of war.
The Farc has said it will release two captive police officers and a soldier this week.
For more than 10 years, military strikes against the ELN and the Farc have severely weakened the rebel groups and limited their ability to attack the country's economic drivers, helping attract billions of dollars in foreign investment.
However, an escalation of violence in recent weeks has killed scores of insurgents and government troops, showing that while the groups are weakened, they are by no means spent.
Inspired by the Cuban revolution and established by radical Catholic priests, the ELN was founded in 1964, the same year the Farc was established.
Attacks against oil and mining installations increased substantially last year, and the government is beefing up the roughly 70 000 troops defending these operations.