The warring sides in Yemen have agreed on extending the ceasefire for another two months in August and October, UN special envoy to Yemen said.

The extension, running from August 2 to October 2, "includes a commitment from the parties to intensify negotiations to reach an expanded truce agreement as soon as possible," the United Nations’ special envoy for Yemen, Hans Grundberg, said on Tuesday.

"The main objective of the current truce continues to be to provide tangible relief to civilians and to create a conducive environment for reaching a peaceful settlement to the conflict through a comprehensive political process," Grundberg added.

Since March 2015, Saudi Arabia and some of its Arab allies have been carrying out deadly airstrikes against the Houthi Ansarullah movement in an attempt to restore power to fugitive former president Abd Rabbouh Mansour Hadi, a close ally of Riyadh.

The war has killed tens of thousands of people, mostly civilians, and resulted in what the UN has described as the world's worst humanitarian crisis.

The children are among tens of thousands of Yemenis, who have died since March 2015, when the kingdom and its allies began taking the Arab world’s poorest nation under a wholesale war.

The fatalities have, in part, been caused by the coalition’s application of Western-provided precision ammunition on crowded civilian centers and residential areas.

The United Nations brokered the truce between the coalition and Ansarullah, which came into effect in April and was extended for another two months on June 2.

Under the truce, commercial flights have resumed from the Yemeni capital of Sana’a to Jordan and Egypt, while oil tankers have been able to dock in the lifeline port city of al-Hudaydah.

"In the coming weeks, I will intensify my engagements...to ensure the full implementation of all the parties' obligations in the truce," Grundberg said, adding he wanted to "put Yemen on a path to sustainable peace."