The 15 British sailors and Royal Marines freed by Iran returned to Britain Thursday as Prime Minister Tony Blair urged the international community to uphold a tough line over Iran's nuclear ambitions and its alleged support for terrorism, according to dpa. As the 14 men and one woman stepped off a British Airway's plane from Tehran in bright sunshine in London, posing briefly for photographers, Blair said the joy over their release was tempered by the "ugly reality" of four British soldiers being killed in southern Iraq Thursday. "Just as we rejoice at the return of our 15 personnel, so today we also grieve and mourn for the loss of our soldiers in Basra who were killed as a result of a terrorist act," said Blair. London has repeatedly accused Iranian forces of being behind attacks on British soldiers in southern Iraq. The group, back in their uniforms after being put in specially- made grey suits by the Iranian authorities for their release Wednesday, were immediately flown to a naval base in Devon, south- west Britain, for debriefing sessions. After 13 days in captivity, they were to be reunited with their families later Thursday. The crew was snatched by Iranian coastguards from patrol boats in the Shatt al-Arab waterway on March 23. While Tehran insisted they were in Iranian waters at the time, Britain has maintained that the boats were well inside Iraqi waters at the time of their seizure. Blair said Thursday that the "dual-track strategy" pursued with Iran during the past two weeks of diplomatic contact had opened "new and interesting lines of communication." "Being open to bilateral dialogue with the Iranian regime, but at the same time mobilizing international support and pressure, whether in the United Nations and Europe, with the United States of America, or with our allies in the region," Blair explained. It would be "utterly naive" to believe that the Britons would have been freed unless "both elements of the strategy had been present," added Blair. Iran, meanwhile, made clear its annoyance of what it called the "internationalization" of the incident by Britain. The capture was condemned by the EU, the United Nations Security Council and individual governments in the Middle East. In Washington, the US State Department said the taking of the captives is another example the Iran "continues to behave in ways that are clearly outside the accepted norm of international behaviour." "This is clearly a regime that, after several decades, continues to view hostage-taking as a tool of its international diplomacy," spokesman Sean McCormack said. US President George W Bush spoke with Blair by telephone on Thursday. During the hour-long conversation, Bush said he was pleased that the sailors he considered hostages were safely in Britain, CNN reported. Blair urged the international community to "remain absolutely steadfast in enforcing its will, whether it is in respect of nuclear weapons or whether it is in respect of the support of any part of the Iranian regime for terrorism, particularly when directed against democratic governments." "The choice in a sense is a choice which I think has to be made by Iran," added Blair. Blair said the captives were freed "without any deal, without any negotiation, without any side agreement of any nature whatsoever." Iran's President Mahmoud Ahmadinejad, who announced the release in a dramatic gesture Wednesday, also said that "no concessions" had been made by the British government, but Britain had pledged that "the incident would not be repeated." Ahmadinejad made a point of bidding a personal farewell to all group members, who were clad in grey suits for the occasion, and showered with gifts and good wishes in front of rolling TV cameras. In Tehran Thursday, Iranian media released footage showing the group drinking tea and receiving gifts before boarding their flight home. Leading Seaman Faye Turney, the only woman among the group, was quoted by the Iranian media as saying to Ahmadinejad: "Apologies for our actions, but many thanks for having it in your hearts to let us go free." Turney, 26, and the mother of a three-year-old girl, had come to symbolize the vulnerability of the captives in several appearances on Iranian TV channels during the period of detention. Ahmadinejad announced the release as a "gift to the British people" at a dramatic press conference in Tehran Wednesday, citing the birthday of the Prophet Mohammed and the "passing of Christ" for the timing of his decision. Britain's Independent newspaper Thursday summed up the mixed feelings among the British public and commentators about the dramatic fashion of the captives' release. "Rejoice" said the paper on its split front page, next to a picture of Blair. But turned upside down, it printed the word "Victory" next to an image of Ahmadinejad.