Britain has blocked European Union efforts to establish an independent international inquiry into the war in Yemen, prompting dismay among human rights groups.

The Netherlands had hoped to garner broad support for its proposal that the UN Human Rights Council (HRC) in Geneva set up an inquiry to examine civilian deaths in Yemen, where the Saudi Arabia-led coalition is accused of committing war crimes.

Instead, with the UK refusing to give its backing, the Netherlands’ proposal for an international inquiry – submitted on Friday by Slovakia on behalf of the EU – was replaced with a much weaker one that the office of the UN high commissioner for human rights (OHCHR) dispatch a mission “with assistance from relevant experts, to monitor and report on the situation ... in Yemen”. This falls far short of what human rights groups and the OHCHR had wanted.

In an open letter to the HRC, Human Rights Watch and other campaign groups claim an international inquiry would help to “establish the facts, collect and preserve information related to violations and abuses with a view to ensuring that those responsible for crimes are brought to justice in fair trials”.

Foreign secretary Boris Johnson last week rejected the need for such an inquiry, arguing that the UK was “using a very, very wide variety of information sources about what is happening to acquaint ourselves with the details” about Yemen.

But the revelation that the UK neutered EU attempts to bring about such an investigation is likely to raise questions about its motives. Since the conflict began, the UK has sold more than £3bn worth of weapons and military equipment to the Saudis and defence contractors hope more deals are in the pipeline.

“Blocking attempts to create an international inquiry is a betrayal of the people of Yemen who have suffered so much during this conflict,” said Polly Truscott of Amnesty International. “It’s shocking. The UK ought to be standing up for justice and accountability, not acting as a cheerleader for arms companies.”

Andrew Smith of Campaign Against Arms Trade said: “For 18 months now, UK arms have been central to the destruction of Yemen. The aid that is being given amounts to a small fraction of the damage that has been caused and pales in comparison to the £3.3bn worth of arms that have been licensed. Theresa May and Boris Johnson must end the arms sales and put a stop to the uncritical support that the UK provides for the Saudi regime.”

Facebook Twitter Pinterest International trade secretary Liam Fox has received a demand from 200 doctors to halt arms sales to Saudi Photograph: REX/Shutterstock

Amnesty and Human Rights Watch claim that, since the Saudi-led coalition entered the conflict in March 2015, 3,799 civilians have been killed and more than 6,700 wounded, including at least 1,444 civilian deaths since the HRC failed to create an international inquiry a year ago. The groups have documented more than 70 “unlawful” coalition airstrikes – on homes, hospitals, markets, civilian factories and schools – some of which, they say, may amount to war crimes, and which have killed at least 913 civilians.

An airstrike on a Doctors Without Borders hospital in August, the fourth during the war, prompted the group to withdraw its staff from six hospitals in northern Yemen and declare a “loss of confidence in the coalition’s ability to avoid such fatal attacks”.

At least 30 civilians were killed when Saudi-led airstrikes attacked a civilian neighbourhood in Yemen’s central port city of Hodeida last Wednesday.

Human Rights Watch also claims that the Houthi armed group and forces allied to it, including those loyal to the former president, Ali Abdullah Saleh, have committed numerous violations and abuses of international human rights and humanitarian law.

Growing disquiet about the UK’s policy on Yemen has seen more than 200 doctors and health professionals sign an open letter to the international trade secretary, Liam Fox, himself a doctor, calling for the UK to suspend arms sales to Saudi Arabia. Fox has been touring Gulf states looking to boost UK exports. He is due soon in Saudi Arabia, where there are hopes he will broker a new deal for British-made Typhoon jets.

The letter, co-ordinated by the campaign group Medact, states: “As health professionals, we have a duty to speak out against all causes of ill health in Yemen. This must include the sale and export of UK weaponry that is fuelling the conflict.”

A Foreign Office spokeswoman said: “The UK is working closely with all parties to secure agreement on a resolution that will help the situation on the ground in Yemen. We remain deeply concerned about the human rights situation in the country, and a political solution to the conflict remains the priority.”