The UK is being urged to halt all sales of riot control equipment to the United States amid concerns they may be being used by police to suppress protests over the death of George Floyd.
Labour said the UK had licensed exports of tear gas and riot shields in the past year and any use for internal repression would contravene the law.
It wants existing and new orders to be stopped pending a review.
Ministers have condemned Mr Floyd’s death but not commented further.
The African-American’s death in police custody in Minneapolis on 25 May prompted an international outcry and sparked a wave of peaceful and violent protests across the US.
Dozens of people have been injured as authorities used tear gas and force to disperse protests which have swept more than 75 cities.
President Trump has urged state governors to mobilise their national guard to control the protests and threatened to send in the military to quell the disturbances.
Labour is urging ministers to clarify whether any UK-made equipment is being used by US police in their operations and, if it is, for all future orders to be immediately suspended.
Shadow international trade secretary Emily Thornberry said police forces across the US had used “excessive force” against peaceful protesters, including children, and it was an “obvious matter of concern” that UK-made equipment could potentially be used to “crush” legitimate demonstrations.
She has urged International Trade Secretary Liz Truss to publish details of all current riot control exports, who has bought them and for what purpose over the past five years.
She said a recent report from the Department for International Trade suggests licences granted include for anti-riot shields, anti-riot guns, portable riot control electric shock devices, tear gas and components for anti-riot guns.
‘Right to know’
Ms Thornberry said ministers should not “shirk” their duty to uphold basic human rights because of the UK’s close relationship with the US, with the two countries historic alliance making it all the more important for the UK to act.
“It has been the policy of successive governments over the past two decades to refuse licences for the export of arms and equipment that might be used for internal repression in the countries to whom they are being sold.
“If there is a risk that any of these riot control projectiles and equipment are being used in the United States against peaceful, unarmed civilians, then the government must act immediately to stop their export
“The British public deserve to know how arms exported by this country are being used across the world, and the American public deserve the right to protest peacefully without the threat of violent repression.”
Meanwhile, Labour’s Dawn Butler has said she is seeking support from MPs from other parties to increase pressure on the government and will release details of names on Wednesday.
The UK government has condemned the killing of Mr Floyd and welcomed the fact that a Minneapolis police officer has been charged with his murder.
But ministers have refrained from criticising President Trump’s response to the ensuing protests, saying they do not want to get involved in another country’s domestic affairs.
Speaking on Sunday, Foreign Secretary Dominic Raab urged a de-escalation in tensions but said it was “not his job” to comments on the President’s handling of the unrest.