Iran is engaging in "inexcusable behaviour" by detaining 15 British sailors and marines, U.S. President George W. Bush said Saturday, calling for the immediate release of theRoyal Navycrew.

"Iran must give back the hostages," Bushsaid at Camp David, the presidential retreat in Maryland. "They're innocent, they did nothing wrong, and they were summarily plucked out of waters."

The comments were the first by Bush on the crisis, and when questioned by reporters, Bush said he fully supports the efforts of British Prime Minister Tony Blair to resolve the situation through diplomatic means.

"I support the prime minister when he made it clear there were no quid pro quos," Bush said.

"The British hostage issue is a serious issue because the Iranians took these people out of Iraqi water."

Iran seized the sailors on March 23, triggering a diplomatic crisis between London and Tehran.

The British government is demanding its personnel be released, saying they were not in Iranian territory.

Under duress

But in video released on Friday and earlier this week, the sailors are shown to be confessing and apologizing, though their statements, according to some experts, were likely made under duress.

Earlieron Saturday, Iranian President Mahmoud Ahmadinejad said the 15 sailors and marinestrespassed in Iranian waters, andcalledBritain and its allies "arrogant" for refusing to say sorry, according to Iran's official news agency.

"The British occupier forces did trespass our waters. Our border guards detained them with skill and bravery. But arrogant powers, because of their arrogant and selfish spirit, are claiming otherwise," IRNA quoted Ahmadinejad as saying during a speech in the city of Andinmeshk in southeastern Iran.

"Instead of apologizing over trespassing by British forces, the world arrogant powers issue statements and deliver speeches," Ahmadinejad said.

Waite offers assistance

Also on Saturday, former hostage Terry Waite told CBC News that he is willing to go to Iran to negotiate on behalf of Britain to try to win the release of the sailors.

Waite has negotiated for hostages in several countries. He himself was held hostage in Lebanon for nearly five years, from 1987 to 1991.

"Because of all of the rhetoric now surrounding this present situation and the way in which it is beginning to erupt into a nasty and violent confrontation, I think it's probably just possible that the Iran may respond to a request made by myself purely on humanitarian grounds," Waite said from Suffolk, England.

"First of all, I would like to see for myself that these people are well to be able to report back to their families. Second, I would like to be able possibly to break this deadlock and talk some common sense rather than just mouth the language of rhetoric.

"I feel we have to cut through some of this nonsense and begin to talk in a way that perhaps may get a response from the Revolutionary Guards in Iran. It's a try. I hope they respond."

Iran's ambassador to Russia, Gholam-Reza Ansari, said the 15 British sailors and marines might be put on trial for violating international law.

Ansari told Russian television Vesti-24 on Friday that they will be tried "if there is enough evidence of guilt."

According to Iran's IRNA news agency, Ansari told Russian television that legal moves against the 15 had already started, "and if charges against them are proven, they will be punished."

One of the captured sailors, Faye Turney, has allegedly written three letters, whichBritish Foreign Secretary Margaret Beckett said showed theservice members were being used for "blatant propaganda" purposes.

Language stilted

Nadim Shehadi, an expert on Iran at London's Chatham House think tank, said with each of the letters, the words become more stilted and political.

Clive Holes, a professor of contemporary Arab studies at Oxford University's Oriental Institute, noted that the second letter refers to a "representative" of Parliament.

"It's obviously been dictated to her," Shehadi said. "There's no way she would phrase it like that."

Britain's Foreign Office said it was checking the claim that the sailors were facing trial, but noted that the ambassador's comments didn't alterits view of what was needed to resolve the standoff.

"This doesn't change our position. We have made it perfectly clear that our personnel were in Iraqi waters and we continue to request immediate consular access to them and their immediate release," an unidentified Foreign Office spokeswoman said on Saturday.

With files from the Associated Press