The head of Colombia's ELN guerilla group on Saturday acknowledged the organization was responsible for last week's abduction last week of the father of Liverpool footballer Luis Diaz, calling it a "mistake" and vowing to work toward his release.

"The retention of Luis Diaz's father by the Northern War Front was a mistake," Antonio Garcia wrote on his Telegram channel.

"Lucho is a symbol of Colombia, that is how we in the ELN feel about him," he added, calling Diaz by his nickname.

The Liverpool striker's parents were abducted in their hometown of Barrancas near the Venezuelan border last Saturday, but his mother was rescued hours later.

Authorities have blamed the kidnapping on an ELN unit and have launched a massive search for Diaz's father, Luis Manuel Diaz. 

The incident threatened to derail high-stakes peace negotiations between the rebel group and leftist President Gustavo Petro, taking place amid a six-month ceasefire.

On Wednesday, the ELN peace negotiators acknowledged to their government counterparts that its Northern War Front unit was holding Diaz's father.

In his Telegram post on Saturday, Garcia said that ELN's central command was overseeing efforts to set the footballer's father free and had instructed its units to cooperate.

"We hope that the operational situation on the ground can be resolved, this is the guidance that the commanders have to expedite the release," Garcia said.

Local media have published a statement purportedly from the Northern Front, in which the rebels explain they had kidnapped Diaz's father for ransom and didn't realize he was the father of the country's football star. The statement could not be independently verified.

Petro, a former urban guerrilla himself, took office last August with the stated goal of achieving "total peace" in a country ravaged by decades of fighting between the security forces, leftist guerrillas, right-wing paramilitaries and drug gangs.

More than 38,000 people have been kidnapped in Colombia over the years, mainly by groups raising funds with ransom money.

The ELN, one of Colombia's last recognized guerrilla groups, started as a leftist ideological movement in 1964 before turning to crime -- focusing on kidnapping, extortion, violent attacks and drug trafficking.

Over 240 people were detained in just the first nine months of this year by illegal groups in the country, 70 percent more than during the same period last year, according to data from the Ministry of Defense.