JERUSALEM — The State Department has, for a second time in two months, reneged on its offer to three Palestinians in Gaza to study in the United States on Fulbright grants, this time citing unspecified security concerns.

The three were part of a group of seven Fulbright winners whose grants were first withdrawn at the end of May when the State Department feared it would be unable to get them out of Gaza because of Israel’s closing of the coastal strip, which the Israelis say is aimed at isolating the Hamas leadership there.

When Secretary of State Condoleezza Rice heard about the withdrawals, she declared Fulbright grants to be an important part of American foreign policy and the scholarships were reinstated. The students needed to undergo individual Israeli security checks in order to leave Gaza and travel first to the American Consulate in Jerusalem for a visa interview and then to fly out.

Four of the seven were cleared but three were told by Israel that they were security risks and could not enter the country. Skeptical American officials asked for details but said they only got broad accusations of links to Hamas; the officials still wanted to offer the grants. The consulate brought from Washington high-priced mobile fingerprinting equipment and sent several officials to the Israel-Gaza border to interview the three Palestinians on July 10.

Three weeks later, on July 30, all three were informed that they had cleared the security screening and were granted their visas.

Two days later, the visas were revoked although not before Israel allowed one of the grantees, Fidaa Abed, to leave Gaza to fly to Washington unaware of his changed status. He was informed at the airport that his visa was no longer valid, flown back to Amman, Jordan, and instructed to return to Gaza. He remains in Amman.

On Monday, the American Consulate in Jerusalem sent letters to Mr. Abed and the two other grantees still in Gaza saying “information has come to light that you may be inadmissible to the United States,” and therefore their visas were being revoked. In Washington, Gonzalo Gallegos, a State Department spokesman, declined to get into specifics, but said that the visas were revoked because “we got more information” about the grantees.

A senior State Department official, who spoke on the condition of anonymity, said that Ms. Rice was very unhappy about how these cases had been handled and that a thorough review had been ordered to prevent a recurrence. The official added that the latest information about the three Palestinians was enough to give pause but that “we really have to scrub it and are now going to take a good look to see if it holds.”

Israeli officials, who had insisted that the three posed a risk, expressed satisfaction that their message had gotten through.

A senior Israeli official said that after the United States had granted the visas, “the process of Israeli-American contacts on the matter did not cease, and more specific information was provided.”

Of the four Gaza Fulbright winners who were permitted to leave, three are in the United States already; one dropped out of the program the night before her departure because she did not want to give up her current lectureship in Gaza.