Press TV - Yemen�s army, backed by Houthi forces, has launched fresh retaliatory attacks against Saudi forces inside the kingdom, leaving an unspecified number of them killed or injured.�

Troops fired ballistic missiles and artillery shells at Saudi mercenaries�in the Najran region,�Yemen�s al-Masirah television network reported.

The al-Hammad and Akefah military bases were hit by the projectiles, including a Zalzal-1 rocket, with more missiles fired at the gathering of Saudi mercenaries in�the nearby Jizan region, it said.

Yemen's�tribal forces�in the southern province of Shabwa carried out their own retaliatory attacks against UAE and Saudi mercenaries, killing at least 10 fighters.

The retaliation reportedly came after helicopters flown by the United Arab Emirates attacked the impoverished country�s southwest, killing seven civilians.

The Saudi kingdom has enlisted the UAE�as its closest ally in the invasion which began in�March 2015 to restore a former government after it�resigned and fled to Riyadh.

The war has claimed thousands since its onset and placed Yemen very close to the edge of famine.

Last year, the Saudi-backed former officials and Yemen�s popular Houthi Ansarullah movement hammered out a ceasefire agreement in Sweden.

The deal has mandated a truce in Yemen�s western al-Hudaydah Province, whose main port receives the majority of vital aid sent for the country.