BELGRADE, Serbia-Montenegro -- Nearly 1,000 people have been arrested in Serbia's crackdown on criminal groups following the assassination of Serbian Prime Minister Zoran Djindjic, a top official said Thursday.

Parliamentary speaker Dragoljub Micunovic spoke as authorities announced further arrests of officials loyal to former President Slobodan Milosevic.

However, the prime suspects -- former paramilitary commander Milorad Lukovic, also know as Legija, and other crime bosses -- remained at large.

"There will be more arrests in the next few days," said Ivan Andric, another top official in the ruling reformist coalition. "There still exist remnants of Slobodan Milosevic's regime."

The government also said deputy state prosecutor Milan Sarajlic, arrested for suspected ties to the gang accused of the Djindjic slaying, has confessed to being on the payroll of organized crime.

In a statement, the government said Sarajlic had admitted to obstructing legal proceedings against key mafia bosses and to undermining investigations into assassinations of prominent Serbian figures in recent years.

Sarajlic's arrest on Wednesday followed the forced retirement of 35 Serbian judges. On Thursday, the head of the Serbian Supreme Court, Leposava Karamarkovic, resigned, citing "political and media pressure."

Djindjic, Serbia's leading pro-Western politician was killed by a sniper March 12 as he stepped out of an armored car in front of the government headquarters in downtown Belgrade.

Authorities accused the so-called Zemun Clan of the killing and imposed a state of emergency, launching a major hunt for leading crime figures, as well as their associates in the judiciary, police and other state services.

Organized crime -- including drug and human trafficking -- flourished during Milosevic's decade-long rule in Serbia, establishing a network that also included dozens of corrupt police and court officials.

After Milosevic was ousted in 2000 and handed over to the U.N. war crimes tribunal to face a trial a year later, Djindjic pledged to curb rampant crime and purge the country of Milosevic's allies. Djindjic also promised to extradite all war crimes suspects, which angered hard-liners in Serbia.

Andric said the police investigation following Djindjic's slaying has pointed to financial links between the Zemun Clan and war crimes fugitives. He did not elaborate.