The Ministry of Defence has tracked 350 alleged breaches of international humanitarian law in Yemen, new figures show.
Campaigners called the number "staggering" and warned UK arms had played a central role in creating one of the worst humanitarian crises in the world.
Saudi Arabia has faced criticism over its role in Yemen's civil war, with warnings the Saudis were "orchestrating what will potentially become the worst famine in the last 50 years".
Defence minister Mark Lancaster said alleged breaches were best investigated by the Saudi-led joint incident assessment team, with the Ministry of Defence's (MoD) figures used to monitor the country's approach.
The UK has sold £4.6 billion worth of arms to Saudi Arabia since its bombing in Yemen began, according to the Campaign Against Arms Trade.
The campaign's Andrew Smith said: "These figures are staggering and shameful, but that is only part of the story. These aren't just numbers on a tracker, they are also people's lives.
"The three year bombardment has seen the destruction of schools, homes and hospitals. Thousands of people have been killed, and yet the arms sales have continued.
"We are always hearing how rigorous and robust UK arms export controls supposedly are, but these figures show how empty those boasts are.
"The people of Yemen are living through one of the worst humanitarian crises in the world, and UK arms have played a central role in creating it."
In January 2017 the Government said it was tracking 252 alleged violations in Yemen.
Ministers have repeatedly insisted they operate one of the strictest arms export control regimes in the world.
They also say Saudi Arabia has a right to defend itself from Houthi rebels operating in Yemen, who have launched missile attacks against the Saudi capital Riyadh.
The new figures were released in response to a written parliamentary question from Labour's Lloyd Russell-Moyle.
He said the figure "is a fraction of the number of war crimes that have been routinely occurring in Yemen", most of which had been committed by the Saudi air force.
"The so called joint incidents assessment team, the self-investigating body set up as a fig leaf to make legal Saudi Arabia's destruction of Yemen, has reported on only 41 allegations of international humanitarian law violations - a fraction of the MoD's fraction. In reality, these statistics are meaningless," Mr Russell-Moyle said.
"They are designed to make the war look tidy and make Britain appear in control of its dubious ally, which is acting against all notions of proportion and restraint. The Tories are simply prioritising private profit over the lives of Yemenis."
In his reply, Mr Lancaster said that as of March 21, the number of alleged instances of breaches or violations of international humanitarian law (IHL) in Yemen listed on the "tracker" database maintained by the MoD is 350.
He said 14 of these are duplicate entries, which means some incidents will have been recorded on more than one occasion due to the way the data is compiled.
Mr Lancaster added: "The MoD does not investigate allegations of Saudi-led coalition IHL violations.
"The Saudi-led coalition is best placed to do this, and does so through its joint incident assessment team.
"MoD analysis of alleged IHL violations is used to form an overall view on Saudi Arabia's approach and attitude to IHL."
Mr Smith, though, said the Government's own analysis "suggests that breaches of international law have become a routine part of the bombing campaign".
He added: "After three years of destruction, what more will it take for Theresa May and her colleagues to stop arming and supporting the Saudi dictatorship?"