Gustavo Petro, the mayor of Colombia's capital, has told thousands of his supporters that the city will become ungovernable if he is ousted from office.

"Bogota will enter a crisis of governability," Petro said when speaking from a city hall balcony on Tuesday night, refusing to accept the government's decision to order him out of office and ban him from politics for 15 years.

Petro has called supporters into the streets for two consecutive nights.

And in front of 40,000 supporters in Bogota's Bolivar Square, he accused the inspector general of doing the bidding of Colombia's far right, which has a history of slaughtering leftist politicians and opposing President Juan Manuel Santos' peace talks in Havana with Colombia's main rebel group.

Petro defended his office saying, "We have governed with zero corruption."

Alejandro Ordonez, Colombia's inspector general, announced the decision to depose Petro on Monday citing the mayor's behaviour in last year's showdown with private garbage collectors as unconstitutional.

A pattern

Ordonez said Petro violated principles of commercial competition and freedom when he fired garbage collection contractors and replaced them with a city-run service.

Ordonez's office has the power to investigate and fire public officials and in 2010 he removed prominent leftist politician Piedad Cordoba from the senate and barred her from political office for 18 years.

Ordonez also dismissed another leftist Bogota mayor in 2011 who was under investigation for corruption related to alleged construction contract kickbacks. He was imprisoned later that year and is currently on trial.

As a senator, Petro investigated the influence of far-right armed groups in Colombian politics. And he uncovered a scandal in 2006 that led to criminal conspiracy convictions of dozens of politicians.

The probe made him a national figure and he finished third in the 2010 presidential election. But his popularity plummeted not long after he was elected mayor of Bogota.

Long-time allies quit his administration and called him stubbornly autocratic as he has sought to place privatised services under municipal control.

Petro is expected to remain in office until all appeals are exhausted. It is not known when elections will be held.