Border guards in Saudi Arabia have regularly opened fire on African migrants seeking to cross into the kingdom from Yemen, killing hundreds of men, women and children in a recent 15-month period, Human Rights Watch said in a report released on Monday.

The guards have beaten the migrants with rocks and bars, forced male migrants to rape women while guards watched and shot detained migrants in their limbs, leading to permanent injuries and amputations, the report said.

The shooting of migrants is “widespread and systematic,” it said, adding that if killing them were Saudi government policy, it would constitute a crime against humanity.

A Saudi government statement dismissed the report as inaccurate.

“The allegations included in the Human Rights Watch report about Saudi border guards shooting Ethiopians while they were crossing the Saudi-Yemeni border are unfounded and not based on reliable sources,” the statement said.

The report provides chilling new details about the conditions along one of the world’s most dangerous smuggling routes, a patch of isolated, war-ravaged territory rarely visited by journalists, aid workers or other international observers.

It focuses on the plight of migrants from Ethiopia, one of the world’s poorest countries, who seek to enter Saudi Arabia — the Arab world’s richest nation and one of the globe’s largest oil exporters — and on the increasingly harsh efforts by the kingdom’s security forces to keep migrants out.

Faisal Othman, a migrant from Ethiopia, told The New York Times that he was trying to cross the border with about 200 others last September when a projectile exploded near the group and shrapnel tore apart the women around him.

“Most of them ended up as remains,” Mr. Othman, 31, said by phone on Sunday from the Yemeni capital, Sana. “They were shredded like crushed tomatoes.”

Destitution pushed people to make the trip, he said.

“They’re just poor people looking to make a living on bare feet, but they face rockets,” he said.

For years, streams of migrants have fled Ethiopia because of poverty, drought and political repression and have headed for Djibouti, where smugglers transport them across the Gulf of Aden to Yemen, the Arab world’s poorest country, which has been torn apart by years of war.

In Yemen, the migrants are taken to territory near the Saudi border that is controlled by the Houthis, an Iran-backed militant group that seized Sana and much of the country’s northwest from the internationally recognized Yemeni government in 2014.

The next year, Saudi Arabia and some of its Arab allies launched a bombing campaign to drive out the Houthis. But it didn’t work, and the war sank into a stalemate and fueled one of the world’s worst humanitarian crises.

Human Rights Watch based its report on dozens of interviews with migrants who have attempted the trip or with their associates; an analysis of hundreds of photos and videos shot by migrants; and an examination of satellite images of the border area.

It describes Saudi border guards firing on groups of migrants with rifles and explosive munitions believed to be mortars or rockets, often killing large numbers of people.

One 14-year-old girl cited in the report recalled seeing 30 people killed around her when Saudi guards opened fire on her group in February. The girl told the researchers that she had hidden under a rock and had fallen asleep, only to realize that other people she thought were sleeping around her were dead.

Other migrants cited in the report said they had been abused by Saudi guards after being stopped near the border. Some were beaten, and others were shot in the limbs after the guards asked them where they would prefer to be shot, the report said.

One 17-year-old boy told researchers that guards had forced him and another migrant to rape two girls in their group after killing another migrant who had refused to do so.

The report estimates that the number of migrants killed between March 2022 and June 2023 is at least in the hundreds but says that the true toll could be in the thousands.

While it focuses on abuses by the Saudi security forces, the report also accuses the Houthis of the widespread abuse of migrants by facilitating smuggling, extortion and detention, which together can constitute human trafficking and torture.

Since the start of Yemen’s war, the country has seen rampant human rights violations and scant efforts to hold perpetrators accountable.

In their effort to beat back the Houthis, Saudi Arabia and its allies have carried out a bombing campaign that has hit weddings, funerals and a school bus full of children on a field trip, altogether killing an untold number of civilians. For their part, the Houthis have fired rockets at civilian targets in Saudi Arabia, deployed child soldiers and controlled the territory they hold with an iron fist, sometimes disappearing dissidents.

The pace of the conflict has slowed since Saudi Arabia and Iran, which supports the Houthis, reestablished diplomatic relations this year and Saudi Arabia began peace talks with the Houthis. But talk of accountably for war crimes has been absent from the discussions.

The last United Nations-backed body established to monitor human rights violations in Yemen stopped working in 2021, after Saudi Arabia and the United Arab Emirates lobbied members of the United Nations Human Rights Council to end the body’s mandate.

Although Monday’s report suggested that the Saudi border forces had become more harsh in targeting migrants, the violence is not new, and there have not been significant international efforts to stop it.

Abdulaziz Yasin, a prominent member of the Ethiopian community in Sana, said the reports of migrants’ being attacked never stopped.

“Every day, there are three, four or five migrants being killed,” he told The Times in phone interview. “Sometimes, 10, 20 or 30 get killed at once. There are a lot of Africans being killed.”

Still, he said, the community believes that it cannot count on any international agency to help.

“We complain to the organizations to no avail,” he said. “How can anyone help us?”

Ben Hubbard reported from Istanbul, and Shuaib Almosawa from New Delhi.