Britain's Foreign Office immediately denounced the video, saying it was "completely unacceptable for these pictures to be shown on TV."
Adding to tensions between the two countries, about 200 angry Iranian youths chanting "Death to Britain" and "Death to America" threw rocks and firecrackers at the British Embassy and tried to rush the compound but were held back by police.
The 15 Britons were detained by Iranian naval units on March 23 while patrolling for smugglers as part of a U.N.-mandated force monitoring the Persian Gulf. They were seized by Iranian naval units near the mouth of the Shatt al-Arab, a waterway that has long been a disputed dividing line between Iraq and Iran. Iran insists the sailors illegally entered its waters, but Britain says the team was in Iraqi waters at the time of their capture.
The captives first appeared on appeared on the state-run Arabic-language TV channel Al-Alam in separate video clips looking relaxed in military fatigues and pointing at the same map of the Persian Gulf.
The first sailor, who was identified as Royal Marine Capt. Chris Air, pointed with a pen to a location on the map where he said two boats left a warship of the U.S-led coalition in Iraq around 8:30 a.m. on March 23. He said the seven marines and eight navy sailors were captured around 10 a.m.
Pointing to the map, he said "we were seized apparently at this point here on their maps and on the GPS they've shown us, which is inside Iranian territorial waters."
"And so far we have been treated very well by all the people here. They have looked after us and made sure there's been enough food and we've been treated very well by them so we thank them for that."
The second sailor, identified as Lt. Felix Carman, pointed to an area on the map and said that location was where he and the 14 others were arrested.
"I'd like to say to the Iranian people, I can understand why you are so angry about our intrusion into your waters," he said.
The newscaster said the two had confessed to "illegally" trespassing in Iranian waters.