Royal Navy: Missiles found by HMS Montrose were linked to Iran after a failure to erase data from a drone, says MoD

The connection is detailed in a dossier of evidence provided to the United Nations by Britain in an attempt to prove Tehran is breaching its rules by supplying weapons to the war in Yemen.

The seizures from within international waters south of Iran early last year included surface-to-air-missiles and engines for land attack cruise missiles.

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Britain handed over its file to the UN as Iranian-made attack drones are used by Russia to pummel Ukraine in Vladimir Putin's invasion.

Officials argue the Islamic Revolutionary Guard Corps (IRGC) has gone to lengths to obscure the components' origins, some of which are copies of Western weapons.

Their quality was assessed to be inferior to the legitimate products and there were clues in the form of miscopied letters.

A picture in the dossier shows one chipboard with what was assessed to be errors: ‘version’ spelt with a lower case l instead of an i and ‘The Netherlands’ spelled with a 1 instead of an l.

One key piece of evidence linking the missiles' to Iran came from a reconnaissance drone found in the February boat alongside surface to air missiles and land attack cruise missile components.

A Ministry of Defence official said: ‘Whilst the external SD card slots on the DJI quadcopter were empty, the internal hard drive had not been wiped.

‘We found 22 test flights, all within the confines of the IRGC Aerospace Force HQ in Tehran.

‘This is the first time we have been able to present evidence to the UN that indicates a direct link between the Iranian state and the supply of these weapons.’

Marines on the HMS Montrose detained the vessels crewed by smugglers identifying themselves as Iranian on January 28 and February 25 last year.

The downwash of a Wildcat helicopter was used to force the crews of the high-speed boats onto the deck so marines could board, according to the evidence passed to the UN.

The smugglers, who are also suspected of running drugs, were released back to their vessels, after it was ascertained there was no grounds to detain them.

Officials believe some parts in the missiles are genuine and have been procured from US, French, German, Dutch and Czech businesses.

But the UN is expected to speak to the manufacturers involved to warn them their components are apparently ending up in Iranian weapons programmes.

A Saudi-led coalition has been fighting the Iran-backed Houthis since 2015, and Tehran's capabilities are believed to be ever improving.

The UN report on possible security council violations is expected to be published shortly.

Defence Secretary Ben Wallace said: ‘The UK is committed to upholding international law and will continue to counter Iranian activity that contravenes United Nation security council resolutions and threatens peace across the world.

‘That is why we have a permanent Royal Navy deployment in the Gulf region, conducting vital maritime security operations and working in support of an enduring peace in Yemen.’

Middle East minister Lord Ahmad added: ‘Once again the Iranian regime has been exposed for its reckless proliferation of weapons and destabilising activity in the region.

‘Iran's sustained military support to the Houthis and continued violation of the arms embargo has stoked further conflict and undermined UN-led peace efforts.

‘The UK will continue to act to protect the security of our partners and hold Iran to account.’