The United Nations World Food Program (WFP) says Saudi Arabia has seized a ship carrying food for Yemen over "humanitarian IT equipment" and diverted it to its southwestern province of Jizan.

The WFP's senior regional spokeswoman, Abeer Etefa, said the MV Mainport Cedar was diverted to Jizan last Thursday while it was traveling from Djibouti to an approved stop at Yemen's port of Hudaydah.

"On behalf of the Yemen humanitarian community, the vessel was transporting commodities including canned tuna, medical supplies for delivery to Hudaydah Port and United Nations emergency telecommunications cluster IT equipment for delivery to the Port of Aden," Etefa told AFP on Wednesday.

"WFP is still in communication with the coalition forces regarding the circumstances of the ship's diversion to Jizan port," she said from Cairo, Egypt. The agency’s senior regional spokeswoman was referring to the so-called Saudi-led coalition against Yemen.

Etefa said the UN agency has resubmitted documents for the "humanitarian IT equipment" as requested by the coalition.

The news comes despite the warning issued by Stephen O'Brien, the United Nations relief chief, on Tuesday about a “humanitarian catastrophe” in Yemen.

Brigadier General Ahmed al-Asiri, the Saudi coalition spokesman, has claimed that the ship carried four declared containers of humanitarian aid but coalition inspectors also found "military communications equipment" elsewhere in the ship.

"There is some equipment that wasn't declared," he said, adding the satellite dishes, solar power units and "crypto systems" are the type of gear used by Yemen's Houthi Ansarullah fighters.

Separately, Riyadh intensified its airstrikes on the Yemeni provinces of Sa’ada and Sana’a, destroying residential buildings.

Meanwhile, Yemen’s al-Masirah television said Yemeni army and popular committees thwarted an attempt by Saudi forces to retake the kingdom’s city of al-Rabou'a, killing and injuring an unspecified number of them. The Yemeni forces had taken control of the city in November last year in retaliation for the Saudi aggression.

Scores of soldiers were also forced to flee the military bases of al-Mosafaq, Jabal al-Dukhan, al-Dabrah in the Saudi province of Jizan as they have been hit by Yemeni artillery shells.

Since March 26, 2015, Yemen has been under military attacks by Saudi Arabia with the declared aim of undermining the Houthi Ansarullah movement and restoring power to the fugitive former Yemeni president, Abd Rabbuh Mansur Hadi, a Riyadh ally.

Nearly 8,300 people, among them over 2,230 children, have reportedly been killed and over 16,000 others injured since the onset of the campaign. The strikes have also taken a heavy toll on the impoverished country’s infrastructure.