The Saudi-led coalition is restricting aid imports to Yemen, Human Rights Watch has reported.
Blocking aid, fuel tankers and placing restrictions on imports is a violation of international humanitarian law, Human Rights Watch highlighted in a new report.
"The Saudi-led coalition should end its unlawful restrictions on imports to Yemen, and Houthi-Saleh forces should stop interfering with aid," said Bill Van Esveld, senior researcher at Human Rights Watch.
"Before even more children suffer and die of preventable causes, the warring parties need to allow fuel, food, and medicine to reach the families that need it."
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Since 2014, the Houthis and President Ali Abdullah Saleh have been in control of the capital, Sanaa, and are prohibiting aid being pushed out to areas beyond their territorial control. Restrictions include not allowing civilians to travel to hospitals for immediate medical attention.
Some 700,000 suspected cases of cholera have hit Yemen, adding to the severity of the humanitarian situation.
All parties to the conflict have a responsibility to citizens under their territorial control to ensure that basic humanitarian needs are upheld. Restricting aid, medical attention and supplies may amount to a violation of the law of war.
The Saudi-led coalition entered the Yemen civil war on request of the internationally recognised President Abd Rabbuh Mansur Hadi, to push back military advancements by the Iranian-backed Houthi group.
The United Nations has repeatedly called for an investigation into violations by all parties in the Yemen civil war. No official United Nations investigation has been conducted yet, but Human Rights Watch and Amnesty International are monitoring hostilities.