Simon Massey, right, and Kaye Turney, the only woman among the 15 British service personnel release by Iran, smile after arriving at London's Heathrow Airport today. The 15 British sailors and marinesn returned home after 13 days in captivity.

LONDON — A British navy crew returned home today from Iranian captivity to the relief of a nation, after President Mahmoud Ahmadinejad announced their surprise release and ended the two-week crisis.

The 15 sailors and marines broke open champagne and changed into fresh uniforms on the flight home. After landing, they smiled and stood at attention before being whisksed by helicopter to the Royal Marines base at Chivenor, southwest of London.

Wednesday's announcement of their release in Tehran was a breakthrough in a crisis that had escalated over nearly two weeks, raising oil prices and fears of military conflict in the volatile region. The move to release the sailors suggested that Iran's hard-line leadership decided it had shown its strength but did not want to push the standoff too far.

Iran did not get the main thing it sought — a public apology for entering Iranian waters. Britain, which said its crew was in Iraqi waters when seized, insists it never offered a quid pro quo, either, instead relying on quiet diplomacy.

Syria, Iran's close ally, said it played a role in winning the release.

Prime Minister Tony Blair welcomed the sailors' return today but called for continued international pressure on Tehran following the deaths of four servicemen in an attack in southern Iraq earlier in the day.

The soldiers were killed in an ambush involving a roadside bomb and small-arms fire, the military said. It was the biggest loss of life for British forces since Nsov. 12, when four were killed while on patrol on a waterway in Basra.

"On the one hand we are glad that our service personnel return safe and unharmed from their captivity, but on the other we return to the sober and ugly reality of what is happening through terrorism in Iraq, terrorism designed specifically to thwart the will of the international community," Blair said.

"Now it is far too early to say that the particular terrorist act that killed our forces was an acted committed by terrorists that were backed by any elements of the Iranian regime, so I make no allegation," Blair said.