ABU DHABI: The UAE said 45 of its soldiers fighting rebels in Yemen were killed in an arms depot blast, while five border guards from Bahrain died in the deadliest day yet for the Saudi-led coalition.

Three days of national mourning were declared for the UAE's highest casualty toll of the six-month-old air war, which Yemen's government blamed on an 'accidental explosion' at a military base in the eastern province of Marib.