Iranian boats tried to impede a British oil tanker near the Gulf – before being driven off by a Royal Navy ship, the Ministry of Defence has said.
HMS Montrose, a British frigate shadowing the BP-owned tanker, was forced to move between the three boats and the tanker, a spokesman said.
He described the Iranians’ actions as “contrary to international law”.
Iran had threatened to retaliate for the seizure of one of its own tankers, but denied any attempted seizure.
Last week, British Royal Marines helped the authorities in Gibraltar seize an Iranian tanker because of evidence it was carrying oil to Syria in breach of EU sanctions.
A spokesman for the Royal Gibraltar Police said they had arrested the Indian captain and chief officer of the Iranian tanker on Thursday, on suspicion of breaching EU sanctions, but neither had been charged.
On Wednesday boats believed to belong to Iran’s Islamic Revolution Guard Corps (IRGC) approached the British Heritage tanker and tried to bring it to a halt as it was moving out of the
Guns on HMS Montrose were trained on the Iranian boats as they were ordered to back off, US media reported. The boats heeded the warning and no shots were fired.
The BBC has been told British Heritage was near the island of Abu Musa when it was approached by the Iranian boats.
Although Abu Musa is in disputed territorial waters, HMS Montrose remained in international waters throughout.
Defence Secretary Penny Mordaunt said the government was concerned by the incident and urged the Iranian authorities to “de-escalate the situation”.
Foreign Secretary Jeremy Hunt added the UK would monitor the situation “very carefully”.
Prime Minister Theresa May’s official spokesman said the government was “committed to maintaining freedom of navigation in accordance with international law”.