Saudi-led warplanes bombarded Yemeni cities at dawn Sunday in a new blow to the UN-proposed truce in the country where millions are threatened with famine.

Saudi-led warplanes bombarded Yemeni cities at dawn Sunday in a new blow to the UN-proposed truce in the country where millions are threatened with famine.

Air strikes hit Saada city in Yemen's north, as well as other places south of the capital Sanaa and in the southern province of Lahj, residents said.

Also in Aden province, the Saudi-US warplanes completely destroyed the Yemeni Company for Grains and Flour Mills in two consecutive raids.

The company used to feed thousands of Yemeni displaced families in Aden.

The UN-proposed humanitarian truce technically went into effect at 20:59 GMT Friday and is supposed to run until July 17, the last day of the holy Muslim fasting month of Ramadan.

But the ceasefire, much needed to rush food supplies to a population threatened by famine, has been flouted by strikes conducted by the Saudi-led coalition.

The ceasefire was declared after UN chief Ban Ki-moon received assurances from fugitive Yemeni President Abedrabbo Mansour Hadi and the Houthi group that it would be respected.

The coalition said it has not received a formal request from Hadi's government to observe a truce, while Sayyed Abdul-Malik al-Houthi said before the ceasefire went into effect they had little hope it would succeed.

More than a week ago the United Nations declared Yemen a level-3 humanitarian emergency, the highest on its scale, with nearly half the country facing a food crisis.

More than 21.1 million people - over 80 percent of Yemen's population - need aid, with 13 million facing food shortages, while access to water has become difficult for 9.4 million people.

The UN says the Saudi-US war on Yemen has killed more than 3,200 people since late March.