JEFFERSON, IOWA, JAN. 22 -- Gary Hart, dogged by reports of improprieties in his campaign finances, said today that he had received illegal campaign contributions, which he will return, from California video producer Stuart Karl.

Citing news reports of Karl's contributions, made by Karl employees, to his campaigns, Hart told reporters in Council Bluffs, "We have found that there may have been as many as four such contributions."

Campaign officials said later that there were only two illegal contributions, totaling $1,500.

The contributions were "in violation of not only the restrictions placed upon campaigns by the Federal Election Commission but also my own standards for campaign practices, and we're going to return that money," Hart said.

Sue Casey, Hart's campaign manager, said the campaign had found only two of Karl's former employees on the list of contributors to the 1988 campaign and said their contributions will be returned "until this is resolved." Casey said Hart campaign officials had asked Karl if it were possible that he had reimbursed contributors.

" 'I don't know. Maybe I better look into it,' " Casey quoted Karl as saying. She said his reply left the campaign in doubt and that Hart operatives decided to return the $750 contributions.

"I cannot stop every person and ask them where they are working or where their compensation's coming from," Hart said. "I think it's pretty standard practice that people employed by corporations volunteer their services in campaigns. . . . There's nothing illegal, so far as I know, with working for a corporation and volunteering your services in a campaign."

Hart campaign counsel Bernie Schneider reiterated today that the 1984 presidential campaign committee has returned all but $8,000 or $9,000 of about $60,000 in excess campaign contributions listed by the Federal Election Commission, as The Washington Post reported this morning, and that the amount of unreturned excess contributions might be as low as $3,000.

"It's all been accounted for except for possibly $8,000 to $9,000, and the amount probably is only about $3,000," Schneider said. "We can't refund this money yet because the '84 campaign doesn't have any money. It owes $1.1 million but we intend to pay it all back and will refund this $8,000 or $9,000 as early as we can."

He said that excess contributions are common in campaigns because of unfamiliarity with the federal campaign laws and that the Hart campaign, as well as all the others, had made many such returns. "All campaigns have the problem of excess contributions and refund the excess," he said. "The '84 Hart campaign has done this many times."

The Miami Herald earlier this week reported allegedly illegal contributions to Hart's 1984 campaign by Karl. The Orange County (Calif.) Register this morning reported excess contributions to Hart's 1988 campaign by three who allegedly were former Karl employees.