BOGOTA - Colombia's President Juan Manuel Santos on Monday signed a law that will allow organized crime gangs to turn themselves in and receive reduced sentences, a move that may help shore up peace in the Andean country.

Criminal gangs, many created by former paramilitary groups, are considered the greatest threat to Colombian security since a peace deal was signed in 2016 with the Revolutionary Armed Forces of Colombia (FARC), ending its part in a five-decade-long conflict that claimed nearly a quarter million lives.

Santos, who leaves office in August, said the law will not allow the gangs any political recognition - as peace with the FARC did - but may allow them to receive reduced sentences if they surrender themselves collectively.

'We have just sanctioned the law that's going to be a very important step for the security of Colombians, a key law for the future of the nation that also allows us to fulfill peace accords,' Santos said.

He said the law could expedite the surrender of the Gulf Clan, which earns millions of dollars from drug trafficking, illegal mining and extortion. The group's leadership offered to turn themselves in September last year.

The United States has offered a bounty of up to $5 million for information leading to the capture or death the Clan's chief, fugitive Dairo Antonio Usuga, known as Otoniel.

The gang has between 1,500 and 2,000 members, according to security sources.

The law would not prevent the extradition of Clan members, Santos said.

The attorney general's office estimates that organized armed groups, including former FARC fighters who refused to adhere to the peace deal, amount to as many as 6,000 members.

Crime gangs have been blamed for killing hundreds of community leaders and human rights workers.

Between January 2016 and June 30 of this year, as many as 311 rights' defenders were murdered, mainly in areas where armed groups are fighting for control of drug trafficking routes and illegal mining left vacant when the FARC signed the peace accord.