Supporters of Bogota's ousted mayor Gustavo Petro protest against his dismissal in front of the mayoral building in the Colombian capital on Wednesday. John Vizcaino / Reuters

The mayor of Colombia's capital Bogota was ousted from his post on Wednesday, President Juan Manuel Santos said, in a controversial decision that could affect May presidential elections and a peace process with left-wing rebels.

Gustavo Petro, 53, a former leftist guerrilla, was dismissed by the inspector general in December last year over alleged mismanagement but stayed pending a run of judicial appeals, the last of which ended on Tuesday and did not reverse the decision.

His dismissal and a 15-year ban from holding public office were viewed as too harsh, even among those who did not support Petro. The case has become a political hot potato amid perceptions the decision may have sought to undermine leftists.

The Inter-American Commission of Human Rights called late on Tuesday for Colombia's highest judicial authority to suspend its decision and allow Petro to serve the rest of his mandate.

But in a declaration naming Labor Minister Rafael Pardo Rueda interim mayor, Santos said that request was not legally binding and that Petro's appeal process had been exhaustive and his dismissal was now unavoidable.

"I have received official communication from the inspector general in which he solicits the dismissal by decree of the mayor of Bogota, Gustavo Petro Urrego, and I have to proceed in conformity with the constitution and the laws," Santos said.

Santos said the Council of State, the last entity to hear the judicial appeal, had informed Petro that he still had other mechanisms of judicial defense to which he could turn, without giving further detail.