CAIRO (AP) — Yemen's Houthi rebels claimed they shot down a U.S. drone over the country's north, as a leading rights group said Wednesday the Saudi-led coalition fighting the Houthis killed at least 47 Yemeni fishermen in bombing attacks on fishing boats last year.

Yahia Sarie, a military spokesman for the Iran-backed Houthis, said in a statement their air defenses downed a U.S. MQ-9 drone Tuesday over the northern city of Dhamar.

"The rocket which hit it was developed locally and will be revealed soon at a press conference," he said.

The U.S. military's Central Command said in a statement that it was investigating the Houthi claims that they attacked an unmanned U.S. drone "operating in authorized airspace" over Yemen.

"We have been clear that Iran's provocative actions and support to militants and proxies, like the Iranian-backed Houthis, poses a serious threat to stability in the region and our partners," said U.S. Army Lt. Col. Earl Brown, a Central Command spokesman.

This was the second U.S. drone allegedly downed by the Yemeni rebels. In June, the U.S. said an MQ-9 Reaper was shot down by the Houthis. It said Iran helped the Yemeni rebels bring down the drone.

For more than a decade, the U.S. has waged a drone war against al-Qaida in Yemen, trying to eliminate one of the most dangerous branches of the terror network. Rights groups have criticized the attacks because of its civilian casualties. An Associated Press investigation found that at least 30 civilians were killed in such attacks in 2018.

The conflict in Yemen began with the 2014 takeover of Sanaa by the Houthis, who drove out the internationally recognized government. In March 2015, the coalition launched its air campaign to prevent the rebels from overrunning the south.

Also on Wednesday, Human Rights Watch said the Saudi-led coalition carried out at least five deadly attacks on Yemeni fishing boats in 2018, killing at least 47 Yemeni fishermen, including seven children.

The New York-based group also said more than 100 Yemeni fishermen are being held in Saudi Arabia, some of whom have been tortured in custody.

There was no immediate response by the coalition to the allegations.

The rights group said it interviewed "survivors, witnesses, and knowledgeable sources about seven fishing boat attacks: six in 2018 and one in 2016." Civilians died in five attacks carried out by small arms and heavy weapons.

It said the fishermen waved white cloths, raised their hands, or otherwise showed they posed no threat. In three attacks, coalition forces did not attempt to rescue survivors adrift at sea, and many drowned, Human Rights Watch said.

The group said the Saudi-led coalition officials who ordered or carried out the attacks or tortured detainees "are most likely responsible for war crimes."

"The naval attacks on Yemeni fishing boats make it clear that the Saudi-led coalition is not only killing civilians through countless illegal airstrikes, but also while conducting operations at sea," said Priyanka Motaparthy, the acting emergencies director for Human Rights Watch.

The group urged a United Nations investigation into the attacks, and the U.N. Security Council on officers and commanders responsible for violations of the laws of war.

It also called for the U.S. and other Western countries to "immediately cease all sales and transfers of weapons" to Saudi Arabia.

"How much more proof do countries continuing to sell weapons to Saudi Arabia need to stop all sales, including of warships, or risk becoming complicit in war crimes," Motaparthy said.

Human Rights Watch says the Houthis have also attacked commercial traffic in the Red Sea.

Saudi-led airstrikes have hit schools, hospitals and weddings, killing thousands of Yemeni civilians. The Houthis have used drones and missiles to attack neighboring Saudi Arabia and have also targeted vessels in the Red Sea.

Iran has repeatedly denied supplying the Houthis with drone or missile technology, both of which the rebels have increasingly used, including to target Saudi Arabia. The kingdom has claimed that Iran supplied the missiles or at least helped the Houthis manufacture them from parts that were in Yemen before the war.

A database tracking the civil war in Yemen, meanwhile, said more than 16,000 people were killed across the county from fighting in the first half of 2019.

The Armed Conflict Location & Event Data Project said that brought the death toll from the war since 2015 to more than 95,000.

It said the deaths this year are running at a rate equal to that of 2018 — the deadliest year of the war on record, when around 30,800 were killed.

The group said that while a U.N.-brokered cease-fire for the Red Sea port city of Hodeida has decreased fighting there, the death toll has increased in the provinces of Taiz, Dhale and Hajjah in 2019.

The group, which receives funding in part from the U.S. State Department and Dutch Ministry of Foreign Affairs, builds its database on news reports from Yemeni and international media and international agencies.

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Associated Press writer Jon Gambrell in Dubai, the United Arab Emirates, contributed to this report.