Iran has detained 10 US sailors after two small patrol boats reportedly drifted into Iranian waters in the Gulf on Tuesday (12 January), US officials say.
Tehran says the crew and the boats "will be returned promptly", Pentagon spokesman Peter Cook told the Associated Press news agency.
According to the Pentagon, the two small boats were sailing between Kuwait and Bahrain when one vessel suffered a technical malfunction. However, Iran's Fars news agency said the sailors were "snooping" in Iranian waters.
Both boats and their 10 crew were seized by Iran's Revolutionary Guard. The incident took place near Farsi island in the Persian Gulf, home to a Revolutionary Guard base. According to Fox News at least one of the boats had drifted into Iranian waters.
"We subsequently have been in communication with Iranian authorities, who have informed us of the safety and well-being of our personnel," a senior administration official told CNN. "We have received assurances the sailors will promptly be allowed to continue their journey."
However Reuters reported that the sailors would be unlikely to be released overnight.
US Secretary of State John Kerry contacted Iranian Foreign Minister Javad Zarif in a bid to resolve the issue, according to Associated Press. The incident follows on from one in December (2015) when Iran fired rockets close to US vessels in the Strait of Hormuz.
In 2007 a British navy boat and its crew of 15 were captured by Iran while on patrol in the same area. The navy said they were in Iraqi waters but Iran said they had entered its territory. The crew was held for 13 days before being released as a "gift" from Iranian President Mahmoud Ahmadinejad.