At least nine Colombian soldiers were killed in an attack with homemade explosives by the country's second-largest leftist rebel band, the military said Wednesday.

The apparent ambush of a patrol by the National Liberation Army, or ELN, occurred in a rural area of Chitaga in the northeastern state of Norte de Santander, the military said in a statement posted online.

It was the biggest blow to Colombia's military since February, when seven soldiers died in combat with biggest rebel band, the Revolutionary Armed Forces of Colombia, or FARC, and comes on the eve of regional trade summit in the western city of Cali that the leaders of Peru, Chile, Guatemala, Mexico, Spain and Canada were expected to attend.

Santos' government has been in peace talks with the FARC for the past six months in Cuba, but they have been stuck on the first agenda item: land reform. The ELN, whose strength the Defense Ministry estimates at 2,000-3,000 fighters, is not involved but is seeking similar negotiations.

The ELN kidnapped a Canadian mining executive, Gernot Wober of Toronto-based Braeval Mining Corp., in January in a state adjoining Norte de Santander.

It said earlier this month that it will not release Wober until his company reverts title to its gold mining concessions in Norosi, in the San Lucas mountain range, to local communities, which the rebels say are the rightful owners.

Santos says there will be no talks with the ELN until the 47-year-old Wober, the company's vice president of exploration, is freed unconditionally.

Both the ELN and the FARC emerged in the 1960s, largely as an outgrowth of rural peasant movements seeking a more equitable distribution of Colombia's agricultural lands.

Also Wednesday, the FARC denied any involvement in the ransom kidnapping of a pair of middle-aged Spanish tourists in Colombia's northeastern state of La Guajira.

Colombia's police chief, Jose Roberto Leon said during a forum in Washington, D.C., that the FARC might have been involved but that it was not yet clear who had abducted Maria Concepcion Marlaska, 43, and Angel Sanchez Fernandez, 49, of the Spanish town of Aviles.

The car they had rented was found abandoned Friday on a road linking Uribia and Cabo de la Vela. They were last seen on May 14 in the coastal city of Santa Marta.

Leon said a ransom was being sought for the Spanish couple but would not specify the amount.


Associated Press Writers Luis Alonso in Washington, D.C. and Frank Bajak in Lima, Peru, contributed to this report.