Yemeni military sources said Arab coalition forces, including the UAE soldiers, were killed in an explosion in Marib
The UAE said 45 of its soldiers engaged in a Saudi-led campaign against Shiite rebels in Yemen were killed in an accidental explosion that the insurgents claimed was caused by rocket fire.
In what was the deadliest day for the coalition since it was formed in March, Bahrain said five of its soldiers guarding the Saudi border with Yemen were also killed.
The Yemeni government said an "accidential explosion" at an arms depot at a military base in the eastern province of Marib killed the Emiratis, but the rebels said their fighters fired a rocket that caused the blast.
Coalition ally Bahrain said five of its soldiers were killed in southern Saudi Arabia where they had been posted to help defend the border with war-wracked Yemen. It did not give a precise location.
However, Yemen's exiled presidency said the Bahrainis died in the same blast that killed the Emiratis.
Abu Dhabi Crown Prince Sheikh Mohammed bin Zayed al-Nahyan, head of the UAE armed forces, underlined in a tweet his country's "determination" to continue supporting the Yemenis against "injustice and aggression".
The UAE, a longtime Western ally, is a key partner in the Saudi-led coalition that in March launched airstrikes against the Houthis as they advanced on the southern port city of Aden, forcing President Abd Rabbuh Mansour Hadi to flee to Riyadh.
The Houthis had seized the capital Sanaa in September 2014.
The coalition has also provided military equipment to loyalist forces and reportedly sent troops, with Saudi media reporting that roughly 1,500 soldiers, most from the UAE, had entered Aden.
The UAE only confirmed last month that its troops were on the ground in Yemen.
Emirati forces in August rescued a British hostage that Abu Dhabi said had been held for more than 18 months by Al-Qaeda in Yemen, although Al-Qaeda in Yemen later denied having held any British hostages.
Earlier this month, sources close to UAE families who have had their sons sent as conscripts to Yemen told Middle East Eye that they were shocked their relatives would be sent to a war zone without any combat experience.
The UAE is estimated to have deployed at least 1,500 troops to Yemen, although no official numbers have been released.
The troops are said to be part of a 3,000 strong Saudi-UAE force, which is rumoured to also include Egyptian soldiers, and is equipped with French battle tanks, Russian fighting vehicles and American troop carriers.