The Bush administration welcomed Thursday's homecoming of 15 British sailors and marines released from Iranian captivity and for the first time since the crisis erupted accused Iran of using 'hostage diplomacy' to boost its status.

With the soldiers safely back on British soil, the White House and the State Department turned up criticism of Iran that had been deliberately toned down during the incident in an effort not to complicate the situation.

From his ranch in Crawford, Texas, President Bush spoke with British Prime Minister Tony Blair in a lengthy video conference, telling him he was pleased that the 15 had returned home, National Security Council spokesman Gordon Johndroe said.

He said Bush commended Blair for his resolve in reaching a peaceful solution to the crisis that began March 23 when Iranian forces seized a British ship and its crew in the Persian Gulf.

Iran says the ship was illegally in its waters but Britain says it was in Iraqi waters. Iranian President Mahmoud Ahmadinejad announced Wednesday he had pardoned the sailors as an Easter holiday gift to the British people.

But Johndroe added that Washington saw no sign that Tehran is now willing to work with the international community, particularly with the U.N. Security Council, which has demanded that Iran scale back its nuclear programs.

"What would show that they're more in line with the international community is to comply with the U.N. Security Council resolution," he said.

At the State Department, spokesman Sean McCormack went further.

He said the incident was part of an Iranian pattern of taking hostages dating back to the seizure of 52 Americans in 1979 and including a 2004 incident in which Iran captured and held another group of British sailors.

"This is clearly a regime that, after several decades, continues to view hostage-taking as a tool of its international diplomacy," McCormack told reporters.

"Let's go back 30 years, let's look at seizing hostages from the American Embassy. Let's look at, twice, within the past three years, seizing hostages from the U.K. There are three examples right there, very clearly, that show a pattern of behavior over an extended period of time," the spokesman said.

The United States regards Iran as the world's leading state sponsor of terrorism and has long accused the Islamic Republic of trying to secretly develop nuclear weapons and has been outspoken in severe criticism of the regime.

But for the duration of the British sailor crisis, U.S. officials had limited their public comments to calling for the release of the crew, fearing they might hinder British efforts to win the release of their sailors, McCormack said.

"In the context of an ongoing hostage crisis, of course we are not going to say anything that could make the situation worse or make it more difficult to realize a peaceful solution," he said. "Absolutely, we're going to tailor our rhetoric."

Both Johndroe and McCormack said the United States had played no role in the release of the British soldiers and reiterated that there is no linkage between the incident and the case of five Iranians held by U.S. forces in Iraq.

Iran has asked for access to the five, who were detained in January, and McCormack said the request is now under "active consideration" by the Pentagon.

Separately, he said, Iranian authorities had informed Swiss intermediaries that they are looking into the case of a former FBI agent who has been missing in Iran since early March.

On Monday, the United States asked Iran, through the Swiss, for any information about the welfare and whereabouts of the missing man, who has been identified as Robert Levinson of Coral Springs, Fla.

Iran then asked for additional data to help in possibly locating the man, which was provided to them on Wednesday, McCormack said.