More than a dozen Saudi military personnel have been killed when allied forces in Yemen shot down a Black Hawk helicopter taking part in Riyadh's military operation against the impoverished Arab country.

Saudi Arabia's SPA news agency confirmed the account on Tuesday. However, there was no comment on the reason behind the incident.

Earlier, military sources allied to Yemen's Houthi Ansarullah movement said the helicopter had been downed earlier in the day in Ma’rib province in northeastern Yemen.

They said at least 13 people, including military personnel from Saudi Arabia and the Arab countries of the Persian Gulf region, were on board the copter when it crashed. The Saudi media said 12 troops were killed.

Military officials in Saudi Arabia swiftly confirmed the downing but said it was mistakenly targeted by a missile interception system in Ma’rib that was operated by the United Arab Emirates. Yemenis said, however, that armed forces loyal to former President Ali Abdullah Saleh, who is allied to Houthis, shot down the aircraft with surface-to-air missiles.

Riyadh said the fatalities included Saudi special forces and crew members. It said an investigation had been launched to determine the circumstances surrounding the incident.

Saudi Arabia launched its deadly campaign against Yemen in March 2015 with the alleged goal of pushing back the Houthis from the capital, Sana’a, and to reinstate a Abd Rabbuh Mansur Hadi, the president who has resigned and is a staunch ally of Riyadh.

The campaign, which lacks any international mandate and has faced increasing criticism, has claimed the lives of more than 10,000 people, most of them civilians.

Saudis and allies have also suffered considerable casualties in the operation on Yemen as official estimates say more than 500 soldiers from Saudi Arabia, the UAE and Bahrain have been killed since March 2015.

Yemenis said on Tuesday that more than 100 Saudi-backed militants were killed in an operation in the southern province of Ta’izz a day earlier. They said most of those killed had been hiding in mountainous regions near the port of Mokha.