Colombian President Juan Manuel Santos said authorities have three people in custody in connection with last week's kidnapping of five mining company employees in the northern province of Bolivar.

The three suspects were part of the group of up to 25 ELN rebels who stormed the mining camp before dawn last Friday and took five of the employees captive, Santos told reporters at the presidential palace after meeting with his top security officials.

The captives - two Peruvians, two Colombians and a Canadian - all work for Geo Explorer, a mining company with operations in Norosi, Bolivar.

Authorities know where the kidnappers went and are on their trail, Santos said, without offering any details.

He added, however, that the pursuers will take every precaution to protect the lives of the captives.

The Colombian government has offered 100 million pesos ($57,000) for information leading to the capture of the kidnappers, while Peru has dispatched two high-ranking police officers to Colombia to join the search.

The ELN, which is the smaller of Colombia's two main insurgencies, targets the mining and oil sectors to signal opposition to the involvement of multinational companies in exploiting the Andean nation's natural resources.

On Christmas Day, the ELN freed two oil engineers the rebels kidnapped in the northeastern province of Arauca. The men were employees of a firm contracted by U.S.-based Occidental Petroleum.