TEHRAN, Iran — One of the 15 British service members held captive in Iran appeared today on the government's Arabic-language TV and said he apologized "deeply" for entering Iranian waters without permission.

Iran also released a third letter supposedly from the only woman in the group saying she has been "sacrificed" to the policies of the British and U.S. governments.

British Prime Minister Tony Blair, whose government has insisted that its navy personnel were captured in Iraqi waters, immediately denounced Iran's treatment of the captured navy personnel and said it would only lead to further isolation for Iran. The standoff has added to tensions over Iran's nuclear ambitions and over allegations that Iran is arming Shiite Muslim militias in Iraq.

"I don't know why the Iranian regime keeps doing this, all it does is heightens people's sense of disgust. Captured personnel being paraded and manipulated in this way, it doesn't fool anyone," he said.

In the video today, Royal Marine rifleman Nathan Thomas Summers was shown sitting with another male serviceman and the female British sailor Faye Turney against a pink floral curtain.

"We trespassed without permission," Summers said. "This happened back in 2004 and our government said that it wouldn't happen again."

It was not known whether the marine spoke under pressure from his captors, but Summers said in the broadcast "our treatment has been very friendly."

Iran earlier broadcast a video showing Turney saying her team had "trespassed" in Iranian waters, and today released a third letter.

The first two letters attributed to Turney said she was sorry the crew strayed into Iranian waters and asked if it wasn't time for Britain to withdraw its troops from Iraq.

The sailors, part of a U.N.-mandated force patrolling the Persian Gulf, were seized off the Iraqi coast while searching merchant ships for evidence of smuggling. Britain insists the sailors were seized in Iraqi waterse.

Britain has frozen most bilateral contacts and referred the issue to the U.N. Security Council, which expressed "grave concern" over Iran's seizure of the personnel.