Amnesty International and Human Rights Watch (HRW) have blamed the Saudi Arabia-led coalition for a missile attack on a Yemen ceramics factory.
The attack on the Radfan factory, which produces civilian goods, killed one person and violated International Humanitarian Law (IHL).
The airstrike occurred on 23 September this yea in the village of Matna in the Beni Matar district, west of Sana'a.
The strike, which used a UK missile supplied in the 1990s, sabotages claims that the Saudi Arabia-led coalition's use of UK military equipment is consistent with IHL, and that the UK monitors compliance with the law carefully.
Amnesty International senior crisis advisor Lama Fakih said: "The UK Foreign Secretary Philip Hammond claims he favours 'proper investigations' into possible breaches of the laws of war in Yemen."
The munition found at the strike site was a PGM-500 Hakim air-launched cruise missile, which was produced by UK firm Marconi Dynamics.
The analysis compared photographed fragments at the strike site with unexploded remnants of the same missile type from a separate strike. It determined both were consistent with the deployment of an air-launched PGM-500 Hakim.
Human Rights Watch UK director David Mepham said: "The latest revelations show UK policy to be both misleading and seriously ineffective. Despite multiple, well-documented cases of violations of the laws of war by the Gulf coalition in Yemen, UK ministers have consistently refused to acknowledge this."
Image: Remnant of a UK-produced missile found at the location of an air strike at Radfan Ceramics Factory, west of Sanaa, Yemen. Photo: courtesy of 2015 Ali Muhammad al-Sawari.