President Reagan said yesterday that his administration has made progress in controlling the spread of nuclear weapons to the point where some nations might obtain "a weapon or two, but they're not going to have enough to threaten the world."

Speaking to a group of high school students for a satellite television broadcast, the president said it is "difficult" but "possible" for nations to divert peaceful nuclear facilities "to the possible making of a weapon."

But he maintained, without providing details, that the administration's policies and international safeguards have been "pretty successful."

"The major parties . . . have nuclear power, nuclear weapons. The two great threats are, of course, the United States and the Soviet Union. But I think we're pretty well on our way to--if not entirely eliminating nuclear proliferation, holding it down to where a country might have a weapon or two, but they're not going to have enough to threaten the world," Reagan said.

Even though Reagan claimed progress in controlling nuclear weapons, many critics in Congress charge that his administration has rolled back the tough non-proliferation policies of presidents Carter and Ford and has taken a less vigilant approach to discouraging the spread of sensitive nuclear technology.

Reagan's comments came during a free-wheeling question-and-answer session with high school students from Houston, Atlanta, New Orleans and St. Louis.

Sitting on a stool in the Old Executive Office Building for the 35-minute broadcast, which was carried to 2,000 schools across the country, Reagan also said he opposes establishing a national holiday to honor the birthday of slain civil rights leader Martin Luther King Jr.

And the president said government workers running welfare programs are "not interested in doing anything to help the people get off welfare."

"Now, I've answered some of your questions with things that I made as factual statements. Don't let me get away with it. If you've got any questions about them, check it out," Reagan said in closing the session.

Asked whether King's birthday should be made a national holiday, the president responded that while he "could see making this a day to remember," he would oppose making "it a national holiday in the sense of business closing down and government closing down, everyone not working."

"I'd like to call to your attention that we only really have a couple of those. George Washington, not even Abraham Lincoln is that kind of a national holiday. There are some states that have made it that way," Reagan said.

The president said he would agree to make the birthday of the civil rights leader a day recognized by a presidential proclamation, "but I would question creating another national holiday type of thing because, as I say, then we open a door. Where do we stop? So far we've stopped with the first president of the United States, George Washington."

Asked whether he is "more concerned" with the defense buildup than with the problems of the poor, Reagan said, "No," and then offered a detailed justification for his ambitious five-year military expansion.

"There was a cartoon that explained it all," he said. " Soviet leader Leonid I. Brezhnev, before he died, was supposed to be talking to a Russian general. And he said to the general, 'I liked the arms race better when we were the only ones in it.' "

Reagan rejected the suggestion of one student that the United States "adopt" the less-developed nations of the world as "colonies."

Then, discussing his Caribbean Basin Initiative, he said it would help islands in the region which are "all democracies." Reagan apparently did not mean to include Haiti, a dictatorship.

Asked to comment on his "powers of persuasion," the president said he has taken his "case to the people," making legislators "feel the heat." But he also said he has made "some great gains in bipartisanship" such as the Social Security compromise rescue plan.