New Delhi, May 31 -- The US military disabled a merchant vessel attempting to run its blockade of Iranian ports by firing a missile into its engine room, Central Command announced on Saturday, marking the sixth time American forces have intercepted a ship seeking to breach the cordon since it was established in April.

The Lian Star, a Gambia-flagged cargo vessel, was struck overnight after it repeatedly disregarded attempts by US forces to turn it back as it sought to reach an Iranian port. The ship received more than 20 separate warnings before the missile strike was authorised, the US military said.

The vessel remained adrift in the Gulf of Oman on Saturday. US forces had not boarded the ship, according to a US official with knowledge...