The Arab coalition has launched new air strikes in at least two Yemeni provinces amid a humanitarian pause that started at midnight the previous day, according to security officials.
Two of Monday's air strikes killed 15 fighters allied with the coalition in the province of Lahij, security officials and field commanders said.
More than 40 fighters were also wounded in the apparent "friendly fire" incident, they said, adding that the death toll was expected to rise.
The strikes occurred near the strategic military base of al-Anad, which is held by Houthis, and which was also hit by coalition jets on Monday.
The coalition also struck north of the port city of Aden.
|Yemen has been rocked by months of fighting between Houthi Shia rebels and Hadi loyalists [The Associated Press]
The US-backed coalition of mainly Sunni Arab Gulf countries has been waging an air campaign since March against the Iran-allied Shia Houthis, who control most of northern Yemen and the capital, Sanaa.
Against this backdrop, Adel al-Jubeir, Saudi Arabia's foreign minister, speaking on Monday after talks with Federica Mogherini, EU's foreign policy chief, denounced "aggressive statements" by Iran.
Jubeir's comments came after Iran's foreign ministry spokeswoman accused Saudi ally Bahrain of making "unfounded allegations" to foment "tension in the region".
The interior ministry in Manama said it had detained two men accused of trying to smuggle weapons from Iran.
Ban Ki-moon, the UN secretary-general, said he urged all the parties to "agree to and maintain the humanitarian pause for the sake of all the Yemeni people" and asked them to act in good faith throughout the pause.
According to the Saudi Press Agency, the humanitarian pause came at the request of Yemen's President Abd-Rabbu Mansour Hadi, who has taken refuge in the Saudi capital Riyadh with much of his government.
An earlier Saudi-initiated humanitarian pause lasted for five days in May but the coalition resumed air strikes immediately after it expired, accusing the Houthis of numerous violations.
A six-day UN-proposed truce which was due to begin just before midnight on July 10 also failed as clashes and coalition air strikes persisted.
Yemen has been rocked by months of fighting between the Houthis and Hadi loyalists, supported by the Arab coalition, leaving thousands dead and 21 million people in need of urgent aid.
Humanitarian crisis of immense magnitude looms in Yemen
Hassan Boucenine, the head of mission for Yemen's Doctors Without Borders (MSF), told Al Jazeera a truce was urgently required by medics as there were now no medicines getting into the country besides those brought in by non-governmental organisations.
"In practice, more than half of the hospitals have stopped working," Boucenine said.
Iona Craig, an independent journalist, told Al Jazeera that people across the country were low on basic staples such as water, rice, flour, fruit, vegetables, and fuel.
"Ground blockades by the Houthi forces have been stopping aid and cutting off places like Aden and preventing food supplies and medical supplies from getting in," Craig said.
Source: Al Jazeera and agencies