Tehran, Iran ? Iran said Monday it was questioning 15 British sailors and marines to determine whether their alleged entry into Iranian waters was “intentional or unintentional” before deciding what to do with them – the first sign it could be seeking a way out of the standoff.

The two countries continued to disagree about where the military personnel were seized Friday, with Britain insisting they were in Iraqi waters after searching a civilian cargo vessel and the Tehran regime saying it had proof they were in Iranian territory.

Britain’s Defense Ministry said they were seized in the Shatt al-Arab, a waterway flowing into the Persian Gulf that marks the border between Iran and Iraq. But the dividing line in the waterway, known in Iran as the Arvand river, has long been disputed.

The Iranian emphasis Monday on the detainees’ intent was a noticeable pullback from the certainty expressed Saturday by Iran’s military chief, Gen. Ali Reza Afshar. Afshar said then that the 15 confessed to “aggression into the Islamic Republic of Iran’s waters.”

Other Iranian officials suggested afterward that the Britons might be charged with a crime – presumably espionage or trespassing – for knowingly entering Iran’s territorial waters.

Deputy Foreign Minister Mehzi Mostafavi took a softer line Monday while saying that the 14 men and one woman were still being interrogated.

“It should become clear whether their entry was intentional or unintentional. After that is clarified, the necessary decision will be made,” Mostafavi said.

The escalating tensions between Iran and the West pushed oil prices Monday to their highest level so far this year. Gasoline futures prices climbed above $2 a gallon to their highest level since last September.

Iran has refused to say where the captured Britons were being held or to allow British officials to speak with them, but assured the British ambassador to Tehran, Geoffrey Adams, that they were in good health.

There were fears in Britain that the fate of the 15 could get caught up in the political tensions between Tehran and the West, including the dispute over Iran’s nuclear program and accusations of Iranian help to Shiite militants in Iraq.

In particular, there were worries Iran might seek to use the prisoners as leverage in trying to get the U.S. to free at least five Iranians detained in Iraq for allegedly being part of a Revolutionary Guard force that provides funds, weapons and training to Iraqi Shiite militias.

Mostafavi denied Iran was seeking a trade.