Around 1,000 soldiers from Qatar's Armed Forces have been deployed to Yemen, as part of the Arab coalition's fight against Houthi rebels, Al Jazeera has learned.
An Al Jazeera journalist, reporting from the Saudi-Yemen border, said the troops were backed by more than 200 armoured vehicles and 30 Apache combat helicopters.
The troops are now reportedly heading to Yemen's Maareb province, to join the Saudi-led coalition already fighting in the area.
Al Jazeera has also learned that more Qatari forces are expected, with the aim of securing the Jawf governorate.
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The news comes as coalition forces pounded the rebel-held Yemeni capital Sanaa with air strikes on Sunday, following the killing of 60 Gulf soldiers in a rebel missile attack on Friday.
The United Arab Emirates had pledged to quickly avenge its heaviest ever military loss, after 45 of its soldiers were killed in Friday's strike, along with 10 Saudis and five Bahrainis, as well as four Yemeni troops.
"Our revenge shall not take long," Emirati media quoted Abu Dhabi Crown Prince Sheikh Mohammed bin Zayed as warning.
"We will press ahead until we purge Yemen of the scum."
Sunday's bombardment was one of the heaviest of the six-month-old air campaign.
Coalition warplanes hit military bases on the capital's Nahdain and Fajj Attan hills and the neighbouring presidential complex, south of Sanaa, as well as a special forces headquarters.
Also targeted were Houthi positions in the northern areas of Sufan and al-Nahda, forcing scores of residents to flee, and rebel positions near the Saudi and Emirati embassies, witnesses told the AFP news agency.
Upwards of 4,500 people have been killed in the Yemen conflict, including hundreds of children, according to the UN which has warned that the country is on the brink of famine.
More than 260 wounded people, mostly civilians, were flown from Aden to coalition member Jordan on Sunday for medical treatment.
Source: Al Jazeera and agencies