Iran's foreign minister accused the United States on Thursday of attempted piracy in trying to prevent Gibraltar's release of an Iranian oil tanker.
Gibraltar decided on Thursday to free the Grace 1, detained off the British overseas territory six weeks ago.
But it said the US Department of Justice had applied to seize the tanker, held on suspicion of smuggling oil to Syria in breach of European Union sanctions.
"The US attempted to abuse the legal system to steal our property on the high seas," Mohammad Javad Zarif tweeted. "This piracy attempt is indicative of Trump admin's contempt for the law."