The Saudi-led coalition battling rebels in Yemen accused the insurgents on Tuesday of having seized a total of 34 aid boats bound for the conflict-wracked country over a six-month period.
Major General Ahmed Assiri said the Iran-backed Huthi rebels had seized the vessels and accused them of blocking humanitarian supplies to the Yemeni port of Hodeida, which they control.
"Aid to the port of Hodeida has been blocked for six months" by the rebels and allied forces, Assiri said in a statement.
"Today there are no more United Nations humanitarian personnel in Hodeida... who can inspect and supervise the distribution of aid and medical supplies."
He said the rebels had intercepted 34 boats carrying aid "in the last 186 days".
Yemen has been rocked by war since the Huthi rebels and their allies expanded from their northern strongholds to seize the capital Sanaa and other parts of the country, prompting the coalition to intervene in support of the government.
More than 7,000 people have been killed and nearly 37,000 wounded in violence since March 2015, and the UN says millions are in need of food aid.
Another 21 million people urgently need health services, according to the UN health agency.