Five foreign workers kidnapped last month from a mining project in northern Colombia were released Friday by the smaller of the Andean nation's two main guerrilla groups, the International Committee of the Red Cross said.

The ELN handed over three Colombians and two Peruvian nationals, the ICRC said in a statement.

All five are employees or consultants with Canada-based Braeval Mining, operator of the Snow Mine project in the northern province of Bolivar.

A sixth captive described as a Canadian citizen and company executive was not freed.

The ICRC sent a team to receive the captives from the ELN, which said it targeted Braeval to press demands for the revocation of mining concessions granted to foreign companies.

The ELN continues to hold a pair of brothers from Germany who rebels grabbed last November as the vacationing retirees were driving in the Catatumbo region, along the Venezuelan border.

Colombian military officials estimate the ELN has some 1,500 combatants.

Earlier Friday, the much larger FARC insurgency released two Colombian police officers who were captured late last month. EFE