Police in Colombia have arrested a 17-year-old who is accused of carrying out more than 30 murders.

The teenage killer, who is known only by his nickname of "Frijolito" which means "little bean", was picked up this week after a four-month manhunt.

Police in Cali on Friday described the boy as "a highly dangerous criminal".

The young man allegedly began killing people around the age of 12 and developed a reputation for ruthlessness as head of a gang of drug traffickers and assassins that terrorised the southern city.

His latest criminal act was reportedly a double homicide at a shopping centre in Cali.

Authorities said he was being held at a juvenile detention centre but that when he turns 18 he will be transferred to a prison.

Cali police chief Hugo Casas described the boy as 'dangerous'. Credit: AP

Cali police chief Hugo Casas said the teenager "probably began his life of crime very young due to gangs and crime rings."

He added: "He is really a dangerous person, it was good to get him and let's say the city is free of a person who could continue doing these deeds outside authority."