Qatar has reportedly deployed troops to Yemen for the first time, according to the Doha-based al-Jazeera news.
One-thousand ground troops, supported by armoured vehicles and helicopters, are reportedly headed for the province of Marib.
Last week, 60 soldiers from the Saudi-led coalition were killed at a base in Marib.
The missile strike by Houthi rebels killed 45 UAE, 10 Saudi and five Bahraini soldiers.
The troops died after an ammunition depot was hit in the town of Safir.
Following the attack, Emirati warplanes launched airstrikes on targets across Yemen.
The Houthi rebels described the attack as revenge for "crimes" committed by the Saudi-led coalition, which has carried out months of air strikes in Yemen.
The coalition is trying to restore the exiled president, who left as the Houthis gained control over much of the country.
The UN says some 4,500 people - including at least 2,110 civilians - have been killed in fighting on the ground and by coalition air strikes since late March.
Coalition countries are thought to have sent several thousand troops to Yemen in an effort to restore President Abdrabbuh Mansour Hadi to power.
They helped southern militiamen opposed to the Houthis retake the southern port city of Aden in July and have since advanced northwards.
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 the capital, 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 militias are fighting back, aided by air strikes led by neighbouring Saudi Arabia