Qatar has sent around 1,000 ground troops to Yemen, Doha-based Al Jazeera television said on Monday, their first reported involvement in a Saudi-backed offensive against the dominant Houthi group.

Military sources said Qatari forces were on their way to Yemen and preparing to join a new push on Houthi positions in the capital Sanaa - though they told Reuters the soldiers had not yet entered the Arabian Peninsula country.

Qatari pilots have joined months of Saudi-led air strikes on the Houthis, an Iran-allied group that seized Sanaa last year, advanced across the country and forced President Abd-Rabbu Mansour Hadi into exile in March.

The reported involvement of Qatari ground troops came amid an escalation of the conflict days after a missile strike that killed dozens of Gulf Arab soldiers.

Al Jazeera's English website said 1,000 Qatari soldiers, backed by 200 armored vehicles and 30 Apache helicopters had been deployed.

The Qatari foreign ministry made no immediate comment on the report.

SAUDI SPECIAL FORCES

A Qatar-based defense source said the number of Qatari troops was less than 1,000. "They are as of now not deployed in Yemen but in Saudi Arabia to protect the border," the source added.

But a local Yemeni official in the oil-producing Marib province east of Sanaa said the Qatari contingent had "crossed al-Wadia border post" between Saudi Arabia and Yemen and were heading to Marib - where Hadi loyalists have been preparing for an offensive against Sanaa. [IDn:L5N11A1C4].

The Saudi-owned al-Hayat newspaper said on Monday that Saudi Arabia had also sent "huge reinforcements" of its elite forces, along with Qatari troops, to Marib.

"Final preparations are being made for a decisive battle, before moving on to liberate Sanaa," al-Hayat said.

Gulf Arab states see the Houthis as proxies for non-Arab Iran, which they accuse of trying to extend its influence into Arab countries, including Syria and Yemen.

Saudi-led forces have helped Hadi supporters drive the Houthis out of the southern port city of Aden in July but have made little progress in other areas since, where the fighting in the Marib and the central city of Taiz remains bogged down.

On Friday, a rocket fired by the Houthis at a coalition military camp in Marib destroyed an arms depot and killed 64 soldiers, including 45 Emiratis, 10 Saudis and five Bahrainis.

Jean-Marc Rickli, Assistant professor at the Department of King’s College London and teaching at the military's Qatar National Defence College, told Reuters: "It is the first time that Qatari ground forces have been deployed in Yemen. So far, the Qatari contribution was only through its Air Force."

"This force will probably take part in the overall war effort to retake the capital after the coalition successfully recapture Aden last month," he added.