Reagan's invitation to Brezhnev: not a exactly a summit, but

President Reagan has opened the door to a summit meeting with Soviet President Brezhnev in New York in early summer.

In a question-and-answer session with the press in the White House Oval Office, Mr. Reagan said he would be addressing the United Nations on arms control in June and that ''I hope very much that Brezhnev will be on hand to address such a group.''

The President then added that it ''would be very well if he (Brezhnev) and I talked.''

''I think this whole subject is one of the most important subjects,'' Mr. Reagan said, referring to nuclear arms control.

Asked if this would be a summit meeting, the President replied ''no,'' saying that he rejected that ''imagery.'' It would not be, he said, a ''full-blown summit.''

Yet, having said that, the President left the door open to discussions on arms control with the Soviet President -- something that might evolve into asummit.

Earlier he had said, when asked whether there would be an arms control summit: ''I think that this would be part of the procedure before we finally arrived at . . .'' Here his voice trailed away.

A possible Reagan-Brezhnev meeting would depend on the Soviet leader's health. There have been reports that he was recently hospitalized. Reagan said that ''we have no confirmation'' that the Soviet leader is ill.

On other major topics, the President:

* Offered to help mediate the dispute between Argentina and Britain over the Falkland Islands and said he hoped the crisis could be settled without additional bloodshed.

He said he would be willing to serve in the ''honest broker'' role if that would be helpful in averting a military clash between British forces and Argentine troops who invaded the islands last week.

* Said he was ''not sorry'' for having said at his press conference last week that the Soviets hold a nuclear superiority over the US. ''We know for sure the Russians know that,'' he said. ''I think the American people ought to be able to know everything they know.''

The Reagan meeting with the press, was the first of a series of regular and frequent question-and-answer sessions planned with members of the news media.

White House aides explained that for some time now the President has been searching for other ways to communicate with the media besides the monthly press conference and interviews.

The President is hopeful, one aide said, that holding these sessions fairly frequently will satisfy those in the media who have been asking for more get-togethers.

Of the possible military confrontation over the Falklands, the President said , ''It's a very difficult situation for the United States because both countries are friends. . . . We are willing to help.''