Iran’s Revolutionary Guards confirmed on Saturday that they had seized an oil tanker in the Gulf as it sailed away from a UAE port, a day after security companies determined they were likely responsible.

“Yesterday morning at 7:30, after a judicial authority ordered the seizure of the cargo of an oil tanker with the trade name Talara and the flag of the Marshall Islands, the Islamic Revolutionary Guard Corps (IRGC) rapid reaction units of the naval forces monitored its movements and intercepted and seized it,” said the IRGC.

“The tanker was found to be in violation of the law by carrying unauthorised cargo,” the statement continued, adding it “was carrying 30,000 tonnes of petrochemical cargo and was heading to Singapore”.

The Iranian news agency Fars said that action was not taken as a measure against any other nation, but was a purely local matter.

The seized cargo, the report said, was made up of Iranian-produced petrochemicals being illegally exported and “the main culprit was an Iranian individual or business”.

The vessel had departed from Ajman in the United Arab Emirates and was heading south through the Strait of Hormuz when it was approached by three small boats, after which it made a “sudden course deviation”, maritime security company Ambrey said.

The US Navy had earlier said it was “actively monitoring the situation”.

“Commercial vessels are entitled to largely unimpeded rights of navigation and commerce on the high seas,” said the US 5th Fleet, which patrols the region.

The Strait of Hormuz, a vital waterway for global oil and liquefied natural gas, has previously been the scene of similar incidents.

Last year, the Revolutionary Guards seized a container ship, saying it had links to Israel, following a deadly attack on Iran’s consulate in Syria blamed on Israel.