Judicial sources said arrest warrants were issued for two former Parmalat chief financial officers, Fausto Tonna and Luciano Del Soldato, and two executives at the Italian affiliate of the Grant Thornton auditing group.
The source added that Wednesday's warrants were issued by prosecutors in Parmalat founder Calisto Tanzi's hometown, Parma.
Tanzi was arrested on Saturday for what US regulators had called one of the "most brazen corporate financial frauds in history".
According to a legal writ, all the men on the police arrest list were suspected of false accounting and fraudulent bankruptcy.
Besides Tonna and Del Soldato, police were also carrying out the arrests of Parmalat accountants Gianfranco Bocchi and Claudio Pessina.
The Grant Thornton executives were named as company chairman Lorenzo Penca and partner Maurizio Bianchi.
The lawyers of Del Soldato, Bocchi and Pessina said arrest warrants had been issued for their clients and that police were at their residences.
Tanzi admits diverting funds
Tanzi had admitted misappropriating hundreds of millions of euros of company funds.
He made the admission during questioning on Monday at Milan's San Vittore prison, lawyer Fabio Belloni said.
"He admitted diverting funds," Belloni said, adding Tanzi said he had funnelled about 500 million euros away from Parmalat and into other companies, including Parmatour, a family-owned tourism company.
Tanzi's shock admission came after authorities had accused him of embezzling more than 800 million euros ($1 billion) from his food conglomerate over the past decade.
A judicial source, speaking to Reuters after Tanzi was questioned on Monday, said the 65-year-old former Parmalat chief had also admitted falsifying company accounts.
"He admitted misappropriation and falsification (of accounts), without knowing the arrangements that were entrusted to his officials," the source said.
Tanzi resigned as Parmalat's chairman and chief executive two weeks ago, amid one of Europe's biggest corporate scandals.
He was arrested at the weekend and held in jail on suspicion of financial crimes at Italy's eighth biggest group, including fraud, false accounting and market rigging. Neither he nor any of the 20, or so others under investigation have been charged.
As shockwaves from the case rippled around the globe, the
US Securities and Exchange Commission announced on Monday it was filing a suit against Parmalat, seeking substantial fines.
In a complaint filed in federal court in New York, the SEC charged Parmalat with securities fraud and accused it of misleading bond investors in "one of the largest and most brazen corporate financial frauds in history."
Calisto Tanzi has been accused of
embezzling more than 800m euros
In addition to the embezzlement charge, authorities have accused Tanzi of working with Parmalat executives and outside auditors to commit fraud and mask the company's financial woes, according to official documents obtained by Reuters.
The accusations are contained in two documents that supported the decision by authorities to arrest Tanzi. One was written by two public prosecutors from Parma, near Parmalat's headquarters and the other by a Milan judge.
Based on statements by witnesses to prosecutors, the documents depict a pattern of market rigging, false auditing, fraud and misappropriation of funds, dating back as far as 1992.
Earlier on Monday another lawyer for Tanzi denied his client and others had colluded to commit offences. "I don't think there is any association, certainly not to commit a crime," Michele Ributti told reporters outside the jail where Tanzi is held.