PHILADELPHIA--The Justice Deparment has added Princeton University, Wellesley College and two other schools to its investigation of antitrust violations in college financial aid policies, The Philadelphia Inquirer reported yesterday.

The investigation--which involves about 20 prestigious schools, including Harvard--is aimed at determining whether schools can confer with each other to offer students similar financial aid packages. Such practices may violate the Sherman Antitrust Act.

Bryn Mawr and the University of Pennsylvania have also been included in the inquiry.

Officials at all four schools said their respective institutions would cooperate with the probe, and all denied the allegations that they violated antitrust laws.

"While we do not believe the college's practices are in violation of the Sherman Act, we will comply fully with the Justice Department's request for information," said Bryn Mawr spokesperson Debra Thomas.

Justice Department spokesperson Amy Brown in Washington refused to comment on the four schools now added to the investigation, or the possibility that others might be included at a later time, the Inquirer said.

The federal department announced in August that it was investigating possible antitrust violations in the establishing of tuition and financial aid at the schools.

Many of the institutions are members of the New England Overlap Group, an organization that meets each year to set up similar financial aid programs for students admitted to more than one school in the group.

The schools contend that the sharing practices avoid "bidding wars" for students and allows applicants to choose a school based on its academic worth rather than the financial aid package it offers.

The four schools are Overlap Group members. But the schools said Monday's notices made no specific mention of any wrongdoing, according to the Inquirer.

"It isn't clear to me that this request for information alleges anything," said Robert Durkee, vice president for public affairs at Princeton. "All we are doing at this point is responding to a request for information."

The Justice Department has asked for material regarding tuition, fees, student financial aid, and faculty and administrative salaries. The information is to cover 1985 through 1988 and must be provided by the end of the month.

William Epstein, an aide to Penn president Sheldon Hackney, told the Inquirer that much of the information--including balance and account papers--is already available to the public.

"Our lawyers are looking into the request," Epstein said. "We intend to cooperate fully with the Justice Department. We believe we are in compliance with the law."

Officials at several of the schools included in the Overlap Group say tuition would be even higher than the $18,000 charged by some for tuition, room and board if bidding wars were being waged to obtain students who needed financial help.