Republican presidential candidate George Bush tonight accused the Carter administration of giving the American people "misleading information" about the hostages in Iran and called on President Carter to tell "the truth behind the facade of diplomatic activity."

In a speech at Harvard University on the 120th day of captivity for the 50 Americans at the embassy in Tehran, Bush said, "We are no closer to solving the hostage crisis than we were at the moment the embassy was seized."

The former chief of the CIA called the hostages "flesh and blood victims of a weak and vacillating foreign policy based on false optimism regarding the state of the world in which we live."

"We have had four months of varied Carter administration approaches to the hostage crisis," he said. "In recent weeks, hopes were raised that critical behind-the-scenes negotiations were taking place that would soon see the hostages set free.

"Now," Bush said, "it seems that despite reassuring words from the White House and State Department, those hopes were false."

Bush said he had refrained from criticizing Carter's handling of the hostage situation and noted approvingly that "the American people have given the president their overwhelming support."

"But," he said, "unity behind any presidential policy is a two-way street. As we said during the days of the Vietnam War, no administration can expect unqualified open-ended support of a policy about which the public is given insufficient or misleading information."

"After four months," Bush said, "the time is long overdue for the Carter administration to be honest with the American people about the reality of the hostage situation. We need to know the truth behind the facade of diplomatic activity that the administration claims has been taking place in recent weeks -- truth that can only come from the president himself, not through, White House or State Department leaks calculated to inspire false optimism."

While focusing his criticism on Carter, Bush also rejected suggestions by Republican rival Ronald Reagan that the United States set a deadline and ultimatum for return of the hostages.And he said he disagrees with Sen. Edward M. Kennedy that "this is a time to enter into public debate over past American policy regarding Iran."

"In short," Bush said, "I disagree with those critics. . . . who, on the one hand, think the answer lies in American apology for alleged past sins, or, on the other hand, think we can free the hostages by bluff and bluster."