BOGOTA — Colombian President Juan Manuel Santos confirmed that his government had begun "exploratory discussions" with leftist FARC rebels to lay the groundwork for a full-fledged peace process.

"Since the day my government took office, I have respected my constitutional obligation to seek peace, and we have undertaken exploratory talks with the FARC, to seek an end to the conflict," Santos said in a speech to the nation.

Santos said Colombian forces would not halt their operations or reduce their presence nationwide while contacts with the Revolutionary Armed Forces of Colombia were continuing.

The president also said in the televised speech that he knew another leftist rebel group, the National Liberation Army (ELN), was interested in being part of the process, and that he was open to their participation.

Santos outlined three key themes for the talks: "We must learn from past mistakes to stop repeating them; any process must lead to the end of the conflict; and, operations will continue and the military's presence will be maintained on every centimeter of national territory."

The president did not say where the discussions had taken place or who took part in them, but noted that the results of the talks would be known "in the coming days."

Earlier in the day, Colombia's former vice president Francisco Santos said the two sides had agreed to open peace talks in the Norwegian capital Oslo on October 5, and then continue the talks in Havana, Cuba.

Founded in 1964, the Marxist-inspired FARC -- Latin America's largest and longest-fighting insurgency -- is believed to have some 9,000 fighters, most of them hiding out in mountainous and jungle areas.

The ELN has another 2,500 fighters, according to government estimates.