[JURIST] Iran detained eight British Royal Navy sailors and seven Royal Marines [UK MOD statement] in waters along the disputed Iraq-Iran border Friday, denouncing [IRNA report] the British forces for their "illegal and interventionist" into Iranian territorial waters. British Foreign Minister Margaret Beckett [official profile] issued a statement [text] Friday, stating that London had "left the Iranian authorities in no doubt that we expect the immediate and safe return of our service personnel and our boats."

The soldiers were seized at the mouth of a river that Iraq refers to as the Shatt al-Arab [Wikipedia backgrounder] and Iran calls the Arvandrud. Control of the river and its use has been a long-standing source of tension [ICE backgrounder] between the two countries. The Algiers Agreement of 1975 [text], in which both parties recognized the waterway as bi-national and divided at the middle of the waterway, was abrogated by former Iraqi President Saddam Hussein [JURIST news archive], which contributed to the 1980-1988 Iran-Iraq War [Wikipedia backgrounder]. In June 2004, six British marines and two sailors were detained by Iran near the same region. The soldiers were released without harm after three days. On Saturday, Iran's official news agency claimed [IRNA report] that the British sailors had "confessed violating Iranian territorial waters." AP has more and provides additional coverage.