Sanaa, July 24 : A total of 13 children were injured in an attack carried out by the Houthi militia against a residential neighbourhood in Yemen's southwestern province of Taiz, a security official said. "Mortar shells were fired randomly by the Houthis on residential houses of a densely populated neighbourhood in the southwestern part of Taiz during the past hours," the official told Xinhua news agency. "A total of 13 children were injured as a result of the shells that landed indiscriminately on the residential area controlled by the government," he said. The attack coincided with the arrival of a high-ranking UN delegation to Taiz, the third largest city in Yemen, to push the warring sides in Yemen to extend the truce that expires on August 2. During the past days, Yemen's Houthis carried out a series of attacks against various areas of the war-ravaged Arab country, as UN Special Envoy for Yemen Hans Grundberg stepped up his effort to extend the Yemeni truce. Several rounds of negotiations between the government and the Houthis were conducted under the auspices of the UN but failed to achieve any progress toward ending Yemen's years-long military conflict. The Houthi militia backed by Iran set new conditions to accept the UN proposal to extend the truce with the Saudi Arabia-led coalition for another six months. As hopes for truce extension begin to fade, political observers said that the possible failure to break the years-long political stalemate on Yemen's issue will badly affect the Yemeni people aspiring for permanent peace. The truce in Yemen, first enforced on April 2 and renewed for another two months on June 2, will expire on August 2. "An extended and expanded truce will increase the benefits to the Yemeni people," Grundberg's office said in a statement, adding that the truce will also provide a platform to build more confidence between the parties and start serious discussions on economic priorities. Yemen has been mired in a civil war since late 2014 when the Houthi militia seized control of several northern provinces and forced the Saudi-backed government out of the capital Sanaa. The war has killed tens of thousands of people, displaced 4 million, and pushed the poor Arab country to the brink of starvation. /IANS