TEHRAN, 25 March 2007 — The Iranian military questioned 15 detained British sailors yesterday and said they confessed to illegally entering the country’s territorial waters as Iran accused Britain of “blatant aggression.”

Iran’s tough comments came after Britain demanded the return of the sailors and denied they had strayed into Iranian waters while searching for smugglers off Iraq’s coast.

The eight Royal Navy sailors and seven Royal Marines were brought to Tehran for questioning.

A top military official, Gen. Ali Reza Afshar, said they “confessed to illegal entry into Iran’s waters.”

“The said personnel are being interrogated and have confessed to aggression into the Islamic Republic of Iran’s waters,” Afshar was quoted as saying by the state news agency IRNA and the semi-official ISNA news agency. He did not say what would now be done with the sailors.

The British sailors, who included at least one woman, had just searched a merchant ship when they and their two inflatable boats were intercepted by Iranian vessels Friday at around 10.30 a.m. near the disputed Shatt Al-Arab waterway, US and British officials said. The Iranian vessels surrounded them and escorted them away at gunpoint.

The seizure of the British sailors came at a time of heightened tensions over Tehran’s nuclear ambitions and allegations that Iran is arming Shiite militias in Iraq.

A British minister met with Iran’s ambassador in London yesterday and demanded the release of the Royal Navy personnel. Lord Triesman, a Foreign Office undersecretary, spent more than an hour with Rasoul Movahedian, demanding the safe return of the sailors.

The Foreign Office described the talks as “frank and civil,” and said the minister also sought assurances about the group’s welfare and consular access.

It is the second time the Iranian ambassador has been summoned to explain his country’s actions in what is developing into a major diplomatic crisis.

Britain has not released the identities of the personnel.

“We still maintain they were in Iraqi waters when they were picked up,” a British diplomat in Tehran said, adding he had no information they had been moved to the capital.

An Iraqi fisherman who said he saw Iranian forces detain them, said yesterday the ship British forces were searching was anchored in Iraqi waters.

The European Union also called for the “immediate liberation” of the captured sailors.

In June 2004, six British Marines and two sailors were seized by Iran in the same waterway. They were presented blindfolded on Iranian television and admitted entering Iranian waters illegally, then released unharmed after three days.

But the latest detention sparked calls among Iranian hard-liners for the Britons to be held until Iran wins political concessions from the West. Several conservative student groups have called on the Iranian government not to release sailors until five Iranians detained by US forces in Iraq earlier this year are freed and UN plans for sanctions against Iran over its nuclear program are canceled.

Some 500 Iranian students gathered on the shore near where the soldiers were captured, shouting “Death to Britain” and “Death to America,” the Fars news agency reported.