The government should stop arms sales to Saudi Arabia amid claims civilians are being killed with UK weapons in the Yemen conflict, says a group of MPs.
The International Development Committee says evidence is "overwhelming" the Saudi-led coalition fighting Houthi rebels has violated humanitarian law.
The committee called for the UK to support an international inquiry into the alleged abuses.
The government said it has a "rigorous" arms export control system.
In a letter to International Development Secretary Justine Greening, the committee said the sale of arms to Saudi Arabia had risen "significantly" during the conflict.
It said close to £3bn worth of export licences for arms had been granted in the last six months.
They include £1bn worth of licences for bombs, rockets and missiles issued in the three months to the end of September last year compared to £9m of licences awarded over the same period the previous year.
"We are shocked that the UK government can continue to claim that there have been no breaches of humanitarian law by the coalition and not only continue sales of arms to Saudi Arabia but significantly increase them since the start of the coalition intervention into Yemen," said the cross-party committee.
"We are convinced that there is more than a clear risk that weapons sold to Saudi Arabia might be used in the commission of serious violations of international humanitarian law.
"The evidence that we have heard is overwhelming that the Saudi-led coalition has committed violations of international law, using equipment supplied by the UK."
The committee's intervention comes after a leaked UN report found the Saudi-led coalition fighting the Iranian-backed Houthis had targeted civilians in air strikes in a "widespread and systematic" way.
The UN panel said civilians were also being deliberately starved as a war tactic and called for an inquiry into human rights abuses.
The war in Yemen escalated in March, when a coalition led by Saudi Arabia entered the conflict on the side of the internationally recognised government to try to oust Houthi rebels from the capital Sanaa and other areas. All sides have been accused of targeting civilians.
The UK supports the coalition and, along with the US and other countries, has been supplying some of the weapons and jets used in the bombing campaign.
But attacks directed against civilians or civilian targets constitute violations of international humanitarian law.
The government claims it has one of the most "transparent arms export control systems in the world" with each licence application assessed on a "case-by-case" basis.
It regularly stresses to the Saudis and the Houthis the need to comply with humanitarian law, according to a spokesman.
International Development Minister Desmond Swayne stopped short of backing an inquiry, telling the Commons: "We've supported the UN Human Rights Council resolution, which requires the government of Yemen to investigate with the support of the UN."
He added that only a peace process to restore the Yemeni government "will end the suffering" in the region.
Saudi Arabia is Britain's biggest market for defence exports, worth $1.7bn (£1.1bn) last year, according to IHS's Global Defence Trade Report.