Police arrested 65 foreign nationals in south Tel Aviv overnight Saturday, following a year-long undercover operation.

The detainees are suspected of committing various drug, violence and property-related crimes, police said.

The undercover agent, whose identity was not revealed, spent 14 months integrating himself into the population of foreign nationals in south Tel Aviv.

“He lived alongside them, made sure to gain their trust and diligently recorded the offenses they committed, and therefore was able to implicate them,” the police said in a statement Sunday morning.

On Saturday night, the agent had invited many of the suspects to a party at a Tel Aviv nightclub, where most of the arrests were made. Many of the suspects were already known to the police.

The undercover sting “provided us with rare intelligence into the toughest criminals, whom we have had difficulty apprehending,” Tel Aviv police commander Bentzi Sau said Sunday. “We will establish an atmosphere of law and order in south Tel Aviv,” he promised.

In recent years, thousands of migrants, most from unstable east African nations, have made their way to Israel. Many have settled in south Tel Aviv, leading to ongoing complaints from residents and reports of crimes.

The government has responded most notably by completing a border fence along Israel’s Sinai border, which dramatically cut down migrants entering the country, and by initiating a repatriation plan where nationals who agree to return to their home country receive a flight and small benefits package for doing so.