Airstrikes by the Saudi-led coalition hit the rebel-held defense ministry in Yemen's capital on Tuesday, said officials, as the United Nations warned more than three quarters of the population was in desperate need of humanitarian assistance.
The airstrikes on Tuesday also targeted the homes of military commanders allied with the rebels in the northwest Sanaa district of Hamdan, the officials said, speaking anonymously as they were not authorized to talk to the press.
Overnight, heavy airstrikes targeted rebel positions in the southern cities of Aden and Ataq, and the northern city of Saada — a rebel stronghold.
The bombing campaign started on March 26, aimed at bringing down the Houthi rebel movement which toppled Yemen's Sunni-dominated government last September.
More than 2,000 people have been killed since the airstrikes began. Last Saturday Saudi Arabia shot down a Scud missile fired by rebels, then on Sunday the coalition bombed rebel headquarters, killing at least 44 people and reportedly injuring 180, mostly civilians.
Saudi Arabia, its coalition of Sunni Muslim states, and Western powers accuse the Houthis of acting as a proxy for Iran, though Iran and the Houthis deny the allegations.
Forces loyal to the deposed president Abdu Rabbu Mansour Hadi, who is in exile in Saudi Arabia, have also been fighting on the ground with the Houthis, who are loyal to the former ruler Ali Abdullah Saleh, since March.
The Houthis have gained control of most of the country since taking Sanaa last September.
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The attacks have failed to defeat the rebels but they have brought about a major humanitarian crisis in what was already one of the poorest countries in the world.
On Monday the UN said around 20 million people — 80 percent of the population — urgently needed humanitarian assistance.
More than 15 million Yemenis do not have access to basic healthcare, with 53 health facilities closed and malnutrition increasing, while 87 per cent of schools in the southern five governorates are closed, according to the UN.
"Our humanitarian colleagues also say that there are more than 250,000 metric tons of grain in stores in Aden and Hudaydah, but that it can't be transported due to lack of fuel and insecurity, nor be cooked because of a lack of cooking gas," UN Spokesperson Stéphane Dujarric told reporters in New York.
Peace talks between the different sides in the conflict are set to start in Geneva on June 14.
The Associated Press contributed to this report.