Iran escalated the drama over the 15 British sailors it seized in the Persian Gulf by announcing Saturday the captured seamen were interrogated and have admitted to straying into Iranian territorial waters.
Iran's military moved the eight Royal Navy sailors and seven Royal Marines — at least one of who was a woman — to Tehran for questioning and said they confessed to illegally entering Iranian waters. Tehran described the incident as a "blatant aggression."
Iran's comments came as the U.N. Security Council met Saturday to consider new sanctions on Tehran for its refusal to meet U.N. demands and halt uranium enrichment. The West fears Tehran's nuclear program is used for arms making, a claim Iran denies.
The Council later Saturday unanimously imposed moderately tougher sanctions on Tehran, hoping to send Iran a strong message it would grow more isolated if it doesn't suspend the controversial nuclear program.
The approved sanctions included ban on Iranian arms exports and freezing the assets of 28 additional people and organizations involved in Iran's nuclear and missile programs. About a third of those are linked to the Revolutionary Guard, an elite corps whose navy had seized the British seamen.
The sailors had just searched a merchant ship Friday morning when they and their two inflatable boats were intercepted by Iranian vessels near the disputed Shatt al-Arab waterway, U.S. and British officials said. The Iranians surrounded them and escorted them away at gunpoint.
Britain immediately demanded the return of the — and denied they had strayed into Iranian waters while searching for smugglers off Iraq's coast.
On Saturday, Iran's top military official, Gen. Ali Reza Afshar, said the seized soldiers, who were taken to Tehran for questioning, "confessed to illegal entry" and an "aggression into the Islamic Republic of Iran's waters." Afshar did not say what would happen to the sailors.
Britain appeared on Saturday to be trying to keep the situation calm.
In London, Foreign Office undersecretary Lord Triesman spent more than an hour with the Iranian ambassador to London, Rasoul Movahedian, demanding the safe return of the 15 and seeking assurances of their welfare and consular access.
Foreign Secretary Margaret Beckett and the Ministry of Defense said the troops were in Iraqi waters at the time they were picked up. Earlier this week, a senior British military official said Iran was paying local militia in southern Iraq to launch attacks on British forces serving in the region.
Friday's incident was not the first time Iran seized British troops in the same waterway. In June 2004, six British marines and two sailors were captured, then paraded blindfolded on Iranian television. They admitted they had entered Iranian waters illegally but were released unharmed after three days.
Since that incident, Iran's hardline President Mahmoud Ahmadinejad came to power. Iranian hardliners have already called for the 15 Britons to be held until Iran wins political concessions from the West.
Some 500 Iranian students gathered on the shore near where the soldiers were captured, shouting "Death to Britain" and "Death to America," the semiofficial Fars news agency reported. Several conservative student groups urged the Iranian government not to release the sailors until five Iranians detained by U.S. forces in Iraq earlier this year are freed and U.N.'s new sanctions against Iran are canceled.
British opposition lawmakers called on the government not to allow Iran to use the capture of the military personnel as a tool in the nuclear dispute.
"The United Kingdom will not be blackmailed. Iran has a choice: to act responsibly; or face greater isolation," said Menzies Campbell, leader of the opposition Liberal Democrats.
With tensions running high, the United States has bolstered its naval forces in the Persian Gulf in a show of strength directed at Iran. There is concern that with so much military hardware in the Gulf, a small incident like Friday's could escalate dangerously.
Afshar, the Iranian officer, warned the United States would not be able to control the consequences if it attacks Iran.
"The United States and its allies know that if they make any mistake in their calculations ... they will not be able to control the dimensions and limit the duration of a war," Afshar said.
His comments seemed to echo that of Ayatollah Ali Khamenei, Iran's supreme leader, who earlier this week warned that Western countries "must know that the Iranian nation and authorities will use all their capacities to strike enemies that attack."
The seizure of the Britons took place in an area where boundaries between Iraqi and Iranian waters have long been disputed. A 1975 treaty set the center of the Shatt al-Arab — the 200-kilometer-long (125-mile-long) channel known in Iran as the Arvand River — as the border.
But Saddam Hussein canceled the 1975 treaty five years later and invaded Iran, triggering an eight-year war. Virtually all of Iraq's oil is exported through an oil terminal near the mouth of the channel.
The seized sailors, from the British frigate HMS Cornwall, are part of a task force that maintains security in Iraqi waters under authority of the U.N. Security Council. Cornwall's commander, Commodore Nick Lambert, said he hoped the detention was a "simple mistake" stemming from the unclear border.
Iraq's military commander of the country's territorial waters, Brig. Gen. Hakim Jassim, told AP Television News that Iraqi fishermen had reported that the British boats were "in an area that is out of Iraqi control."