WASHINGTON: Iran's Revolutionary Guards have released 10 United States (US) sailors and their patrol boats after investigations showed they had entered Iranian waters unintentionally, a statement said Wednesday.

"It was determined that the detained American Marines did not enter Iranian waters intentionally. Following their apology, they have been released to international waters in the Gulf," state television quoted a Guards statement as saying.

Two US Navy boats were taken into Iranian custody on Tuesday but Iranian Foreign Minister Mohammad Javad Zarif assured US Secretary of State John Kerry that the US sailors would be allowed to continue their journey promptly, another US official said.

"Earlier today, we lost contact with two small US naval craft en route from Kuwait to Bahrain. We subsequently have been in communication with Iranian authorities, who have informed us of the safety and well-being of our personnel. We have received assurances the sailors will promptly be allowed to continue their journey," the official said, speaking on condition of anonymity.

The US craft patrolling the Gulf were somehow disabled and drifted into Iranian territorial waters at which point they were detained by Iranian Revolutionary Guards and taken to Farsi Island in the middle of the Gulf, Fox News reported.