Bogota  - Colombian authorities on Thursday arrested lawyer Guillermo Valencia, the brother of the country's Interior and Justice Minister Fabio Valencia, over alleged ties to a runaway drug boss.

Guillermo Valencia, who was until recently head of the public prosecutor's office in Medellin, was arrested in that city and was set to be taken to Bogota for questioning, the authorities said.

The scandal broke early last month, when the public prosecutor's office launched a probe of the minister's brother over alleged ties to Daniel Rendon. Rendon, known by the alias "Don Mario," reportedly leads a paramilitary drug-trafficking gang and is wanted by the authorities.

At the time, Guillermo Valencia was transferred from Medellin to the town of Tunja, although he was finally sacked once telephone conversations became public that suggested he was close to members of Rendon's entourage.

One of those conversations suggested that Valencia interceded to have at least one person removed from a police wanted poster with photographs and information about the bosses of the criminal organization.

The man to whom Valencia was talking, a businessman who was arrested in August, promised an all terrain vehicle (ATV) in return for the favour. The authorities recently seized such a vehicle from among Valencia's possessions.

The political opposition in Colombia has demanded the resignation of the Interior and Justice minister over his brother's behaviour. The minister, however, noted that criminal responsibility is personal and that he cannot be held accountable for his brother's wrongdoing, although he believes Guillermo Valencia is in fact innocent.

The opposition insists it is "unheard of" that a brother of the Interior and Justice minister should be in legal trouble over ties with the paramilitaries and with drug gangs. (dpa)