President Reagan, in a letter to an Illinois anti-abortion leader, has said that opposition to Supreme Court nominee Sandra Day O'Connor is being "stirred up" principally by one "vindictive" person in Arizona.

The letter itself is stirring up more anger among conservatives. Reagan did not name the "vindictive" person, but conservatives think he is referring to one of their most prominent anti-abortion activists, Arizona Dr. Carolyn Gersters.

In addition, data on O'Connor's voting record contained in the letter appears inaccurate, and conservatives again are charging Reagan with being uninformed on the history of his nominee.

Gersters reportedly started the criticism of O'Connor's abortion voting record in the Arizona legislature, and that led to an outcry from anti-abortionists following the O'Connor nomination.

Reagan's Aug. 3 letter, verified by the White House yesterday, was in response to a letter of protest sent to him by Marie Craven, secretary of the Illinois Pro-Life Coalition.

"I believe that most of the talk about the appointment was stirred up principally by one person in Arizona," Craven quoted Reagan's letter as saying. "I have done a great deal of checking on this and have found this person has something of a record of being vindictive," the president added without elaborating.

Reagan went on to describe, inaccurately, O'Connor's legislative vote in 1974 on a rider prohibiting abortions at the University of Arizona hospital. Reagan wrote Craven that the Arizona Senate "turned that down" because its members, including O'Connor, thought it was unconstitutional.

Legislative records indicate that the rider became law with Senate approval. O'Connor voted against it, according to legislative records.