Pop star Justin Bieber and a group of his friends were seen in a Bogota tunnel painting graffiti on the walls escorted by a Colombian police patrol, media outlets said Thursday.

Wearing his habitual cap and hood, the star took advantage of his stay in the Colombian capital after the concert he gave on Tuesday to leave his signature and several written bits of advice on how to "overcome expectations" in one's life on the concrete.

Bieber and his pals were at work on their graffiti artwork along a stretch of tunnel wall about 40 meters (yards) long on 26th Street near the Bogota City Council building under the curious gaze of a group of fans and City TV cameras, which continued filming despite the protests of the singer and his bodyguards.

The police who were on hand reminded the bodyguards that Colombia enjoys freedom of the press.

Evidently, the singer was able to obtain permission to place graffiti on the wall, although this activity is punishable by a warning in Colombia and there is currently a controversial case making its way through the local court system about a young graffiti artist who died at the hands of the police.

The director of the Colombian police, Gen. Rodolfo Palomino, predicted that controversy would arise due to the different treatment the two young men received and he told La F.M. radio that things have to "evolve" because "graffiti is the expression of a feeling, of a motivation."

The Canadian singer last Tuesday kicked off in Bogota the South American swing of his Believe Tour, which will also take him to Ecuador, Brazil, Paraguay, Argentina, Chile and Uruguay. EFE