CHICAGO — A federal judge gave preliminary approval Wednesday to a $640 million settlement of claims against four drug companies accused of knowingly selling HIV-tainted clotting products to hemophiliacs. HIV is the virus that causes AIDS.

People with hemophilia who used blood-clotting products between 1979 and 1985 and who are HIV-infected would get roughly $100,000 each under the agreement approved by U.S. District Judge John Grady.

The attorney for an HIV-positive teen-age hemophiliac from Abbot believed to have been infected by the tainted clotting products said Wednesday it is unlikely his client will accept the settlement.

Attorney Jonathan Huntington in Dover-Foxcroft said no decision had been made, but the possibility of accepting the $100,000 offer to compensate his client, J.R. Rollins and his family, “were not good,” given what the family and Rollins, 17, have endured.

The Rollins family is pursuing their own suit and would forfeit further legal action against the makers of the blood products if they accept the offer, Huntington said. The family is seeking an unspecified amount of damages from the drug companies.

Rollins’ suit alleges that the defendants — Germany’s Bayer AG; Baxter International Inc. of Deerfield, Ill.; the Armour Pharmaceuticals division of French-owned Rhone-Poulenc Rorer; and Alpha Therapeutic Corp., a division of Japan’s Green Cross Corp. — were negligent in the manufacture and marketing of the blood-clotting agent AHF. The clotting agent allegedly contained the virus for a period of time in the mid-1980s.

The Rollins suit alleges the companies failed, knowingly or as a result of negligence, to warn hemophiliacs and their doctors of the risks of HIV transmission through the use of clotting agents. The suit further alleges the companies could have taken measures to heat-treat the clotting agent to remove the HIV.

Grady’s ruling would also affect survivors of hemophiliacs who died of AIDS as well as family members and others who have contracted HIV from a person with hemophilia.

Lawyers for the companies and hemophiliacs estimate the number of people eligible for the settlement at 5,000 to 6,000.

Although some hemophilia activists contend the offer is inadequate, Grady said it “has sufficient earmarks of fairness.” The judge set a Nov. 25 hearing for testimony from those who are affected by the settlement.

David Shrager, lead attorney for the hemophiliacs, said the settlement is probably the only way many of them can get compensation for their suffering.

Shrager said most who have sued the drug companies in the past have lost their cases. Those who have won later had their victories overturned on appeal. Individual suits by about 800 people, including Rollins, remain pending.

“The legal obstacles have been great,” Shrager said. “There have been problems of product identification and there is the statute of limitations. This is an offer that deserves consideration.”

Hemophiliac groups say the companies purposely failed to protect them by refusing to treat the products with heat that would kill the virus, and by manufacturing the products from blood products taken from people at high risk for AIDS, such as drug abusers. The companies contend that reliable AIDS-killing treatments weren’t available until the mid-1980s.

Terms of the settlement say $600 million will be distributed to victims, $40 million will pay for expenses and lawyers fees in the decadelong litigation.

Notices will be sent next week to those affected by the settlement. They will have until Oct. 15 to notify the court whether they will accept the offer. If they reject it, they will have the option to sue the drug companies.

“This is an effort to resolve litigation and to improve and enhance the relationship with our customers,” said Phil Beck, the attorney for Alpha Therapeutic Corp. “The settlement is fair and reasonable and in the best interests of the companies and the plaintiffs.”

The drug companies admit no guilt with the agreement. They have the option of dropping the offer if too many people reject it, Beck said.

Some advocates have complained that the same companies contributed $240,000 per person as part of a similar settlement in Japan. The companies said the legal system is more stringent in that country, necessitating the higher payment.

The advocates also contend that the number of AIDS-infected hemophiliacs in the United States probably is closer to 10,000. If so, each person would get less than $100,000.

In the decade since the contamination became known, more than 4,500 hemophiliacs have died from AIDS.