Around 400 Yemeni politicians and tribal leaders launched talks in Saudi Arabia on Sunday on the future of their war-torn country, but the Shiite Houthi rebels who control the capital and much of northern Yemen are not participating.

The meeting came as a five-day cease-fire that has been repeatedly violated was set to expire. The Saudi-led coalition and the rebels have blamed each other for the violations, as fighting on the ground has continued throughout the pause.

The Houthis have rejected the main aim of the three-day talks -- the restoration of Yemen's exiled president -- and the location of the negotiations in Saudi Arabia. The absence of the Houthis means the national dialogue is unlikely to end the violence.

The U.N. envoy to Yemen, Ismail Ould Cheikh Ahmed, opened the meeting by calling on all parties to ensure that the shaky cease-fire leads to a lasting truce.

"I call on all parties to refrain from any action that disturbs the peace of airports, main areas and the infrastructure of transport," said Ahmed, who delivered the speech on behalf of U.N. Secretary-General Ban Ki-moon.

Since late March, Saudi Arabia has led airstrikes against the Houthis and allied military units loyal to former President Ali Abdullah Saleh. The air campaign is aimed at weakening the Houthis and restoring to power internationally recognized President Abed Rabbo Mansour Hadi, who fled the country in March in the face of a rebel advance.

"This conference taking place today is in support of politics and community, and rejects the coup," Hadi told the gathering.

He urged a return to the political road map through which Saleh stepped down after more than three decades in power following a 2011 Arab Spring-inspired uprising. Saleh's ouster and the road map was backed and overseen by the six-nation Gulf Cooperation Council, which is headquartered in Saudi Arabia, as well as the U.N. and the U.S.

Among those taking part in the conference are members of Saleh's former ruling party.

Yemen's conflict has killed more than 1,400 people -- many of them civilians -- since March 19, according to the U.N. The country of some 25 million people has endured shortages of food, water, medicine and electricity as a result of a Saudi-led blockade. Humanitarian organizations have been scrambling to distribute aid before the end of the truce.

The U.N. agency for children said it has distributed supplies "which can provide primary health care to over 24,000 people and treat 3,500 severely malnourished children."

UNICEF said 115 children have been killed and 172 have been wounded in the conflict since the beginning of the airstrikes on March 26. Thirty schools and 23 hospitals have been attacked, it said, without saying who was responsible.