RIO DE JANEIRO, Brazil — Investigators in Rio de Janeiro arrested 63 police officers and 11 alleged drug traffickers on Tuesday after a year-long bribery probe and ongoing efforts to stamp out police corruption ahead of the World Cup in 2014 and Summer Olympics in 2016.

The arrests, part of a crackdown on Rio's historically violent and corrupt state police force, follow an investigation into bribes that drug dealers allegedly paid to police officers so they could operate without interference.

The arrests were centered around Duque de Caxias, one of the crime-ridden suburbs that make up the gritty outskirts of the coastal metropolis.

The officers and others arrested were charged with crimes including drug trafficking, corruption and kidnapping. The activities, state police officials said, were carried out in the favelas, or slums, north of central Rio.

Officials have gone to great lengths to clean up Rio and the surrounding state of the same name before the international sporting events, which are expected to attract hundreds of thousands of visitors.

But the violence, corruption and drug trade that have plagued Brazil's second-biggest city thrive in all but the few neighborhoods where the events will take place.

Combined with construction delays, missed budgets and a stagnant Brazilian economy, security concerns add to growing uncertainty ahead of the competitions.

On Tuesday, officials at the International Olympic Committee reminded Rio that "time is ticking" ahead of the games.

State officials, however, pointed to Tuesday's arrests as progress on the security front.

Dubbed "Operation Purification," the probe and arrests reflect the ongoing effort to curb unruly elements of a police force with ties to the criminals they are supposed to pursue.

"It's important that we cut into our own flesh so the institution can earn legitimacy," said Mariano Beltrame, Rio's state security secretary.

Erir Ribeiro, commander of the police force, added: "We can no longer accept the humiliation of deviant conduct practiced by a few."

Following Tuesday's detentions, officials fired the commander of the police battalion where the arrested officers were deployed.

Because of low salaries compared to much of the private sector, police often turn to crime.

In addition to collusion with drug gangs and other criminals, some Rio police run the infamous "militias" that control vast swaths of the state and illegal activities ranging from extortion to murder to unlicensed public transport.

Tuesday's arrests came on the same day that another officer, a state police corporal, went on trial for the killing last year of Patricia Acioli, a Rio judge known for her work investigating militias.

As the trial got under way, the corporal, who helped investigators build their case, gave a dramatic confession and said he deserved to be punished.

"I regret the disgrace I did my family and hers," said the corporal, Sergio Costa Junior, according to an online account published by newspaper Estado de S. Paulo. "I strongly believe in justice. Do justice with me."

The corporal is one of 11 state police officers accused in the murder. Acioli was shot more than 20 times outside her home.