The British defence secretary Michael Fallon has seen government analysis indicating that UK-made cluster munitions were used by the Saudi-led coalition in the current conflict in Yemen, sources have told the Guardian.

It is understood the government’s own investigations back up media reports that such cluster bombs have been deployed in the war, in which Britain is helping to train Saudi forces. A source told the Guardian that Fallon is among the ministers to have known about the analysis for about a month.

But it is understood ministers have still not been given definitive confirmation one way or the other by Saudi Arabia, which has publicly denied the allegations and claimed that UK-made cluster bombs found are the relics of old conflicts.

The revelation is likely to increase calls on the government to reconsider exports of arms to Saudi Arabia, which have already grown since the US suspended a planned sale of precision-guided munitions last week.

Some of the UK-manufactured cluster bomblets gathered in northern Yemen. Photograph: Amnesty International

A Saudi-led coalition has been fighting a Houthi rebel uprising against the Yemeni government since 2015, with Britain providing some military training assistance.

Establishing the truth is important because the UK is a signatory to a 2010 international treaty banning the use of cluster munitions. The weapons leave mini-bomblets that can explode much later, killing civilians. The Cluster Munitions Convention commits the UK to disposing of all cluster munitions and working to prevent their use by anyone else. Saudi Arabia is not a signatory.

A senior defence source said the issue of UK-made cluster munitions was “something that has been raised at the highest possible levels and we have been trying to establish definitively for some time”.

The Ministry of Defence would not reveal the contents of the analysis but a government spokesman said: “The government takes such allegations very seriously. We have analysed the case carefully using all available information, considering all possibilities, and raised the issue with the Saudi-led coalition.”

Reports from ITV, Sky News and Amnesty International have all pointed to bombs made in the UK and exported before the ban having been dropped in the ongoing war.

Philip Hammond, then the foreign secretary, pledged in May that the Ministry of Defence would investigate fully and seek concrete assurances from Saudi Arabia that there has been no use in the current conflict of British-made cluster munitions.

At that time, ministers said the government does not possess any evidence that such weapons have been deployed, and suggested that the bomb found by Amnesty International could have been from a previous conflict in the region, adding that the last supply of this weapon to the Saudis was in 1989.

Since then, further footage has been published by ITV and Sky, showing the leader of the rebel Houthi government, Abdulaziz bin Habtour, accusing Britain of war crimes. “They have sold cluster bombs to Saudi Arabia,” he told Sky News earlier this month. “They know the Saudis are going to drop them on Yemen ... in Sa’dah and in Sana’a and other provinces.I don’t think they are guilty of war crimes, I believe so. They are participating in the bombing of Yemen’s people.”

Concerns about the Saudi military using weapons in Yemen that have been exported from the UK have been repeatedly raised in prime minister’s questions by Angus Robertson, the SNP leader in Westminster.

Robertson said: “I too have heard from informed sources about the Saudis dropping UK-made cluster munitions in Yemen. It is totally unacceptable and piles pressure on the Ministry of Defence and Foreign Office to come clean. The US has now stopped supplying Saudi with guided missiles and it’s high time for the UK to adopt an ethical approach.”

When it was raised last week at prime minister’s questions by Robertson, Theresa May told the House of Commons that any allegations of breaches of international humanitarian law would be “properly investigated”. She also defended the UK’s support for Saudi Arabia, saying the intervention in Yemen is backed by the United Nations and “the security of the Gulf is important to us”. She added “the intelligence we get from Saudi Arabia has saved potentially hundreds of lives here in the UK”.

Earlier this month, No 10 delivered a rebuke to Boris Johnson, the foreign secretary, for critical remarks at a conference saying that Saudi Arabia was engaged in puppeteering and proxy wars in the Gulf. Downing Street said that was not the official government position. The UK is a firm ally of Saudi Arabia in the war in Yemen, with British military personnel helping train its troops to how to target bombs. Britain has also sold billions of pounds in defence equipment including planes to the Saudi military since the start of the war.

Last week, Tobias Ellwood, a Foreign Office minister, revealed he had formally urged all six Gulf states to sign up to the international convention banning the use of cluster munitions. He said Britain condemned the weapons’ use and that he had personally told the six Gulf foreign ministers that they should sign up to the treaty. “I absolutely condemn the use of cluster munitions,” he said. “They lie around the battlefield until it turns into a civilian arena, and that is why they cause damage.”

Ellwood also said he would support an independent inquiry into war crimes by both sides in the Yemen civil war if the Saudi’s own inquiry proved unsatisfactory.



