Ronald Reagan talked tough in Texas and Tennessee today, accusing President Carter of deceiving the American people with a phony increase in the U.S. defense budget.

As he campaigned in military-minded Texas two days before the Republican primary here, Reagan also suggested at one point that the loss of "national prestige" in the Iranian crisis may ultimately be more important to the United States than the lives of the 53 hostages.

Reagan's charges about the defense budget were based on a contention that Carter was achieving a pledged 3.1 percent boost in the 1981 fiscal year defense budget by artificially lowering the 1980 budget.

"The Carter White House didn't want an honest increase," Reagan said. "So, it demanded that the Defense Department carry out a deceptive bookkeeping trick."

Reagan said that there has been no real increase in defense spending, despite Carter's promises to the American people to do so.

After the news conference in which Reagan made these charges, his aides cited an April 8 memo by John Quetsch, deputy comptroller for the Department of Defense, to Secretary of Defense Harold Brown. The memo discusses 1980 defense budget decreases, apparently politically motivated, that would have the effect of making the increase in the 1981 budget seem larger in percentage terms.

The contents of this memo previously have been reported by various newspapers, including The Washington Post.

Reagan's allegation was part of a concerted attack he has been making on Carter on the national defense issue, which in Johnson City, Tenn., later today, he called one of the central issues of the presidential campaign. While Carter has been saying he will keep the nation's defense "second to none," said Reagan, "it is already second to one -- the Soviet Union."