LONDON, April 5: All 15 sailors and marines held by Iran for almost two weeks arrived at Heathrow Airport around lunchtime on Thursday. British Prime Minister Tony Blair, speaking to reporters in Downing Street as the plane landed, welcomed their return while taking an unexpectedly tough line, warning Iran that the international community could not accept their support of terrorism.

The Britons were seized while conducting a routine early morning anti-smuggling check on a merchant vessel in the Gulf on March 23.

The prime minister said there were “elements of the Iranian regime” that were “financing, arming and supporting terrorism in Iraq”.

His comments came after four British soldiers were killed by a roadside explosion near Basra, southern Iraq. Mr Blair paid tribute to their bravery and said: "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.”

He said he was glad they had been released and knew that their families would be “profoundly relieved” to hear the news.

Speaking alongside Foreign Secretary Margaret Beckett outside Number 10, the British prime minister stressed on Wednesday that the UK had adopted a “firm, calm, measured" approach throughout the situation, “not negotiating but not confronting”.

He also had a reconciliatory message for the Iranian people. “The disagreements we have with your government we wish to resolve peacefully through dialogue.”

His comments came after Iranian President Mahmoud Ahmadinejad had announced that the personnel would be freed immediately as a “gift to the British people”.

Iran had previously claimed that each member of the group had confessed to illegally entering Iranian waters.

But the UK government insisted the sailors and Royal Marines were in Iraqi waters when Iranian gunboats seized them.