Britain is in "direct bilateral communication" with Iran as it tries to win the release of 15 detained sailors and marines, British Defence Secretary Des Browne said today.
"We are anxious that this matter be resolved as quickly as possible and that it be resolved by diplomatic means and we are bending every single effort to that," Browne told BBC television. He declined to give details but said: "We are in direct bilateral communication with the Iranians."
Earlier, about 200 Iranian students threw rocks and firecrackers at the British Embassy in Tehran, calling for the expulsion of the country's ambassador over the standoff.
Several dozen policemen prevented the protesters from entering the embassy compound, although a few briefly scaled a fence outside the compound's walls before being pushed back, according to a reporter at the scene.
The protesters chanted "Death to Britain" and "Death to America" as they hurled stones into the courtyard of the embassy. They also demanded that the Iranian government expel the British ambassador and close down the embassy, calling it a "den of spies."
Britain's Foreign Office said there had been no damage to the compound
Earlier, British government and defence officials refused to comment on a newspaper report that a Royal Navy captain or commodore would be sent to Tehran as a special envoy in an effort to negotiate the return of the sailors.
The official would deliver an assurance that British naval crews would never deliberately enter Iranian waters without permission, the Sunday Telegraphnewspaper reported.
Britain's Foreign Office and Ministry of Defence said they would not comment on negotiations, or on options being considered. "We will continue to conduct our diplomatic discussions in private," a Foreign Office spokesman said on the government's customary condition of anonymity.
However, transport minister Douglas Alexander said Britain was engaged in "exploring the potential for dialogue with the Iranians."
"The responsible way forward is to continue the often unglamorous, but important and quiet diplomatic work to get our personnel home," Alexander told the BBC's Sunday AMprogram.
A spokeswoman for the ministry of defence declined to comment on claims officials had lost optimism of a quick end to the standoff, saying speculation about diplomatic efforts threatened to hinder progress.
British Foreign Secretary Margaret Beckett appeared to soften rhetoric against Iran yesterday - though she stopped far short of the apology sought by many in Iran.
"I think everyone regrets that this position has arisen," Beckett said in Bremen, Germany, before returning to England. "What we want is a way out of it."
The Foreign Office and Blair's Downing Street office said it welcomed US President Bush's intervention - calling yesterday for the release of the sailors and marines and labeling their capture by Tehran "inexcusable behavior."
"Iran must give back the hostages," Bush said. "They're innocent, they did nothing wrong, and they were summarily plucked out of waters."
Eight British sailors and seven marines were detained by Iranian naval units March 23 while patrolling for smugglers near the mouth of the Shatt al-Arab, a waterway that has long been a disputed dividing line between Iraq and Iran.
Tehran says the crew was in Iranian waters, but Britain insists its troops were on the Iraqi side of the maritime border.
Iranian President Mahmoud Ahmadinejad called world powers "arrogant" for failing to apologise.
"Instead of apologising over trespassing by British forces, the world arrogant powers issue statements and deliver speeches," Iran's official IRNA news agency quoted Ahmadinejad as saying during a speech in the southeastern city of Andinmeshk.
A poll published today in the Sunday Telegraphnewspaper found that 66 per cent of respondents trusted Blair and Beckett to resolve the crisis, while 28 percent did not. Only 7 per cent thought the government should be preparing to use military force.
AP