BOGOTA (Reuters) - The Gulf Clan crime gang, considered Colombia’s largest criminal organization, has declared a month-long ceasefire for Christmas and New Year and invited other armed groups to also lay down their weapons for the festivities.

The gang, also known as the Usuga Clan and the Autodefensas Gaitanistas, is accused of operating drug trafficking routes in partnership with Mexican cartels, extortion and illegal gold mining. Fighting the group is considered one of the country’s top security challenges.

“We declare a unilateral ceasefire of offensive military action nationally in all of the areas where we are present, between Dec. 8, 2018 and Jan. 10, 2019,” the group said in a statement posted on its website on Sunday.

“We invite all armed groups who are part of the conflict to adopt a similar position to ours, always with the goal of contributing to the cause of peace,” it said.

It has long been traditional for Colombia’s armed groups to declare holiday and election period ceasefires. The now-demobilized Marxist FARC rebels regularly stopped armed offensives during Christmas.

The United States has offered a reward of more than $5 million for information leading to the capture of Gulf Clan leader Dairo Antonio Usuga, who is known as Otoniel.

Many crime gang members are former paramilitary fighters who returned to armed groups after a demobilization process more than a decade ago.