Warplanes from the United Arab Emirates have launched air strikes on several targets across Yemen.
The strikes came a day after 45 Emirati soldiers died in Yemen in a missile strike claimed by Houthi rebels.
Ten Saudi troops fighting the rebels were also killed in the Houthi attack, Saudi officials said on Saturday.
A Saudi-led coalition is trying to restore the exiled president, who left as the Houthis gained control over much of the country.
The UAE also announced on Saturday three days of mourning for its troops, who died in a rebel missile strike on an ammunition depot in Marib province.
Bahrain also said that five of its troops were killed on Friday, reportedly in the same blast.
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.
According to Emirati state media, Emirati air strikes hit Houthi rebel targets in a number of places inside Yemen.
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