Forty-five soldiers from the United Arab Emirates' military and five troops from Bahrain have been killed while taking part in a Saudi-led military campaign against Yemen's Houthi rebels, in the deadliest day for Gulf forces since the conflict began.

Pro-government Yemeni security officials said the UAE troops were killed on Friday when a Houthi missile hit a weapons storage depot near their position in the province of Maarib, about 120km east of the capital Sanaa.

The UAE state news agency WAM initially put the death toll at 22 but updated it to 45 late on Friday.

Officials from the Houthi media office in Sanaa confirmed a Soviet-era Tochka missile was fired at the site.

The office of Yemen's exiled president, Abd-Rabbu Mansour Hadi, said that Yemeni troops had also died in the incident, without giving numbers.

The UAE has declared a three-day period of mourning for the soldiers.

President Sheikh Khalifa "mourned the brave Emirati soldiers who were killed in Maarib in Yemen in defence of truth and justice," state news agency Wam reported.

In a separate development on Friday, Bahrain, another Gulf country involved in the coalition's conflict against Houthi fighters, announced that five of its soldiers were killed in southern Saudi Arabia where they had been posted to help defend the Saudi border. It did not give a precise location.

However, Yemen's exiled presidency said the Bahrainis died in the same blast that killed the Emirati forces.

Deadliest day

Saudi Arabia and a coalition of other mostly Arab states have been fighting since March to restore Yemen's exiled government and to repel the Houthis, who took control of the capital Sanaa in September last year.

Friday was by far the deadliest day for the Emirati military since the conflict began, and the deaths are believed to be the country's highest number of military casualties since the UAE federation was founded in 1971.

At least five other Emirati soldiers have been killed in Yemen since the offensive began.

Emirati ground forces and hardware have been playing an increasingly prominent role in the conflict in recent weeks, though officials have not made clear the full extent of their role or the numbers of troops involved.

Source: Agencies