The Royal Navy is sending 30 Marines to the Gulf for a training exercise amid Iranian attacks on two oil tankers.

Elite soldiers from 42 Commando will leave their Plymouth barracks to form Special Purpose Task Group 19, deploying on Royal Navy ships from Britain's new Bahraini base.

Earlier reports that the Marines are being deployed to protect British ships in light of the tensions were tonight denied by the Ministry of Defence.

An oil tanker is seen after it was attacked at the Gulf of Oman, in waters between Gulf Arab states and Iran on Thursday - Donald Trump has said the two attacks had Iran 'written all over it'

Royal Marines Commandos - including the 42 Commando unit being dispatched to the Gulf - taking part in arduous training exercises in Plymouth recently

A diagram showing the U.S. and Iranian forces in the region and the location of recent attacks on oil tankers and a Saudi oil pipeline, which have escalated Middle East tensions

'This is a pre-planned training deployment and is in no way related to the ongoing situation in the Gulf of Oman,' an MOD spokesman said.

Foreign Secretary Jeremy Hunt said London had concluded Iran was 'almost certainly' responsible for Thursday's tanker attacks, The Times reported.

Donald Trump has said the oil tanker attacks had Iran 'written all over it', rejecting Tehran's vehement denial.

Attacks on tankers have brought chilling echoes of the 1980s Tanker War which resulted in a one-day naval battle between the US and Iran.

The US military on Friday released grainy footage it said showed an Iranian patrol boat removing an 'unexploded limpet mine' from one of the tankers.

Britain has backed the United States in blaming Iran for the tanker attacks and on Saturday, Iran summoned the British ambassador to complain about its 'unacceptable stance,' ISNA news agency reported.

'Rob Macaire, Britain's ambassador to Tehran, was summoned to the foreign affairs ministry... following the false remarks made by the British foreign affairs minister,' the foreign ministry said in a statement carried by the official IRNA news agency.

Other nations have urged caution. Germany said the video was not enough to prove Iran's role, while U.N. Secretary-General Antonio Guterres called for an independent investigation to determine responsibility.

China and the European Union called for restraint.

Meanwhile Labour leader Jeremy Corbyn said Britain should 'ease tensions' and 'not fuel a military escalation that began with US withdrawal from the Iran nuclear agreement.'

Hunt trashed his notion that the UK lacked 'credible evidence,' and branded Corbyn 'pathetic' for his 'virulent anti-Americanism.'

In a statement, the Foreign Office said 'no other state or non-state actor could plausibly have been responsible' for the incident.

The Royal Marines elite commandos (pictured in training recently off Plymouth)

Iran has repeatedly threatened to block the Hormuz Strait, a narrow seaway vital to the world's oil supplies, in the event of a conflict with the US.

Iranian Foreign Minister Mohammad Javad Zarif tweeted that the US had 'immediately jumped to make allegations against Iran without a shred of factual or circumstantial evidence.'

The US has also accused Iran over May 12 sabotage attacks on four tankers anchored in the Gulf of Oman off Fujairah.

UN Secretary-General Antonio Guterres called for an independent investigation.

'It's very important to know the truth (and) that responsibilities are clarified,' he told reporters at UN headquarters in New York.

'Obviously that can only be done if there is an independent entity that verifies those facts.'

President Donald Trump on Friday charged Iran with attacking oil tankers in the Persian Gulf and warned Tehran their actions will not be taken lightly. 'Iran did do it,' Trump said on 'Fox & Friends' when he called in to the morning show for an interview

The oil tankers hit Thursday morning were 10 nautical miles apart and heading for Asia when they were struck by explosions after passing through the Strait of Hormuz, some 25 nautical miles off Iran's southern coast.

The Front Altair was carrying naphtha, a refined petroleum product, when it was hit by three explosions, according to Norwegian officials.

Blocking the Hormuz Strait would be a relatively low-tech, high-impact countermeasure Iran could take against any attack by the United States, and would severely disrupt global oil supplies.

But Mr Trump played down the threat.

'It's not going to be closed, it's not going to be closed for long and they know it. They've been told in very strong terms,' he said on Friday, referring to Iran.