A unit of the 53-year-old guerrilla group said it was behind the deadliest of the three attacks that killed seven policemen and injured several dozens over the weekend.
“The veracity of the alleged ELN statement is being verified,” said Santos, whose administration has been negotiating peace with the guerrillas for almost a year.
The attack on a Barranquilla police station killed five policemen and further aggravated the crisis that emerged after the warring parties failed to extend a three-month ceasefire earlier this month.
The responsibility for two other attacks was not immediately claimed by any of the armed actor in the conflict that has battered Colombia since the 1960s.
Santos and former Vice-President Gustavo Bell will meet in Bogota to discuss the chief negotiator’s progress in negotiations to resume the ceasefire and the peace talks, according to Caracol Radio.
Bell spent last week in meeting with the guerrilla leadership in the Ecuadorean capital of Quito.
According to the ELN, these talks have not progressed due to “conflicting mandates” of the negotiators.
Colombia’s conservative opposition, led by hard-right former President Alvaro Uribe, has called for an end of the talks with the country’s last-standing guerrilla group.
Centrist and leftist thought leaders urged “we can not return” to violence that has marked Colombia’s past.
The crisis in the peace talks with the ELN come less than two months before congressional elections and in the middle of a peace process with the FARC, until last year the largest illegal armed group in Colombia.
More than 265,000 Colombians lost their lives in the armed conflict that displaced more than 7 million citizens.