Pro-government forces in Yemen have retaken the country’s largest airbase in a battle with Houthi rebels, a spokesman for the forces told the BBC.
Heavy casualties have been reported at al-Anad airbase, north of Aden, after intense fighting there in recent days.
It comes after pro-government forces, backed by air strikes from a Saudi-led coalition, retook Aden in July.
The Saudis are leading a campaign to push the rebels back and restore the government, which it is sheltering.
Troops and armoured vehicles from the United Arab Emirates – a key member of the coalition – are also said to have arrived in recent days.
Military officials quoted by the Associated Press news agency say the foreign troops are helping the pro-government forces operate sophisticated weapons, including tanks. The New York Times said the troops had been involved in the fighting at al-Anad.
However, local journalists told the BBC that Emirati troops had recently disembarked in Aden and were deployed as advisers, rather than in combat, while a Yemeni military official denied foreign troops had landed in Yemen.
Analysis: Jonathan Marcus, BBC diplomatic correspondent
The reported deployment of Leclerc tanks and other armoured vehicles from the United Arab Emirates, which have been seen unloading in the southern port of Aden over recent days, represents the first major ground involvement by the Arab coalition ranged against the Houthi rebels.
It is a signal that the air campaign launched in March of this year has its limits and it’s a sign too that the Saudi-led coalition is willing now to become more engaged in the fighting.
US sources, cited by the New York Times newspaper have confirmed the deployment in broad terms though its exact composition remains unclear.
Some estimates suggest numbers in the order of ,3000. There are indications that the arrival of the heavy armour has already had an impact in helping seize the al-Anad air base – an important asset that could provide a launch-pad for more extensive operations against the rebels.
Al-Anad used to be a base for US troops overseeing drone attacks on al-Qaeda. It was overrun by Houthi rebels as they advanced south in March, forcing President Abdrabbo Mansour Hadi to flee.
“The al-Anad airbase is now back in the hands of President Hadi’s men,” Nasr Alkaid, a spokesman for the pro-government forces, told the BBC.
He said the loyalists were still battling rebels about 4km (2.5 miles) from the base.
Why is there fighting in Yemen?
- Northern Shia Muslim rebels known as Houthis, backed by forces loyal to Yemen’s ex-president, took over parts of Yemen, including Sanaa, and forced the government into exile in March
- The rebels accused the government of corruption and of planning to marginalise their heartland within a proposed federal system
- Forces loyal to the government, and southern militia, are fighting back, aided by air strikes led by neighbouring Saudi Arabia
There has been no comment from the Houthis on the latest claims that the base has fallen.
If confirmed, the recapture of the airbase could remove a major obstacle for government forces on the road to Taiz, Yemen’s third-largest city, where pro-Hadi militia have been clashing with rebels.
Sunni power Saudi Arabia regards the Houthis as proxies of Shia rival Iran. It alleges Iran has provided the Houthis with weapons, something Iran and the Houthis deny.
The rebels – backed by forces loyal to the former President, Ali Abdullah Saleh – say they are fighting against corruption and marginalisation of their northern powerbase by Mr Hadi’s government.
The conflict has killed almost 4,000 people in Yemen, nearly half of them civilians, since it escalated with the Saudi-led campaign in March, according to the United Nations.
Thousands of Yemenis have fled the fighting, many of them sheltering in the tiny nation of Djibouti, across the Horn of Africa.