Blair said the sailors from the HMS Cornwall frigate did not act illegally and were in Iraqi waters.


"What [Iran] should understand is that we cannot have a situation where our servicemen and women are seized when actually they are in Iraqi waters under a United Nations mandate, patrolling perfectly rightly and in accordance with that mandate."


Tehran's reaction


Iran condemned as "provocative" Blair warning's.


"The media campaigns and provocative ... remarks regarding the violation of Iranian territorial waters by the British sailors are doing nothing to help settle the affair," Mohammad Ali Hosseini, Iranian foreign ministry spokesman, said on Tuesday.


"The British service personnel entered Iranian waters illegally  and the case will follow its legal and judicial course."


Hosseini said that British diplomats would be able to meet the 15, who include a woman, once investigators had completed questioning them about what they had been doing in Iranian waters.


Margaret Beckett, the British foreign secretary, who cut short a  visit to Ankara on Tuesday to report to MPs on the row with Iran, had earlier renewed calls for immediate consular access to the captive  personnel.


She said: "If indeed they are being detained in reasonable circumstances,  then we can see no reason why they should not have contact with  people from the British government."


US account


US officials said on Tuesday the sailors were seized by Iranian naval forces after boarding an Indian-flagged commercial ship suspected of carrying smuggled cars.


It is the first detailed account of the operation being conducted by the British sailors and marines at the time of their capture.


"[The British sailors] are in completely good health. Rest assured that they have been treated with humanitarian and moral behaviour"

Mohammad Ali Hosseini, a spokesman for Iran's foreign ministry

"It was an Indian-flagged vessel. It was suspected of being involved in automobile smuggling [into Iraq]," said commander Kevin Aandahl, a spokesman for the US Fifth Fleet.


Aandahl said US officials knew the GPS co-ordinates of the Indian ship at the time the incident occurred, but would not release them publicly.


Iran has said it is interrogating the 15 to determine if they intentionally strayed over the border or if it was inadvertent.


Mohammad Ali Hosseini, a spokesman for Iran's foreign ministry, said Tuesday the sailors and marines in detention are healthy and have been treated humanely.


"They are in completely good health. Rest assured that they have been treated with humanitarian and moral behaviour," Hosseini said.


Hosseini would not say where the Britons were being kept and reiterated that their case is under investigation and would follow Iranian procedures.

Source: Agencies