Yemen crisis: Dozens killed by 'air strike' near refugee camp
An air strike has killed at least 40 people at a refugee camp in northwest Yemen, aid workers have said.
State media said Saudi planes were responsible, but the Yemeni foreign minister said "artillery strikes" by Houthi rebels were to blame.
A Saudi Arabian-led coalition has been targeting Shia Houthi rebels across the country in support of Yemen's embattled president, Abdabbuh Mansour Hadi.
Fresh strikes on Monday evening hit an arms depot in Sanaa.
Residents from the area around nearby were seen fleeing their houses after the explosions, eyewitnesses and military sources said.
Saudi naval forces have begun blockading Yemen ports to stop the movement of rebels and to prevent them bringing in arms, coalition forces said.
The al-Mazrak camp has been housing Yemenis displaced by the conflict between the Houthis and the central government since 2009.
The International Organization for Migration (IOM) said 200 people were also wounded in the al-Marzak bombing. It initially reported that 45 people died but revised this down to 40.
Aid agency Medecins Sans Frontieres (MSF) said 29 dead bodies and 34 injured people were taken to a hospital it operates near the camp.
"It was an air strike," said MSF's Middle East programme manager Pablo Marco.
Mr Marco said 500 new families had arrived at the camp over the past two days as fighting intensified across the country.
There were reports of further unrest in the south with rebel forces shelling the town of Daleh. A local government official said eight people had been killed.
There was also heavy fighting reported in Aden after rebels pushed into the city's north-eastern suburbs.
The Houthis have said their aim is to replace President Hadi's government, which they accuse of being corrupt.
He fled the country for the Saudi capital Riyadh, as rebels advanced on the port city of Aden, where he had taken refuge.
Former President Ali Abdullah Saleh - whose supporters are fighting alongside the Houthis - has called for a truce.
But Saudi Arabia has vowed to defend Mr Hadi's government through air strikes and has the backing of several Arab League members.
Abdul Malik al-Houthi, leader of Houthis, has refused to surrender to what he called the "unjustified aggression" by the Saudi authorities and their allies.
Shia power Iran, which Sunni-ruled Saudi Arabia accuses of backing the rebels, has also demanded an immediate halt to the strikes, which it said violated Yemen's sovereignty.
The Houthis: Zaidi Shia-led rebels from the north, who seized control of Sanaa last year and have since been expanding their control
President Hadi: Fled to Saudi Arabia after rebel forces advanced on his stronghold in the southern city of Aden
Al-Qaeda in the Arabian Peninsula: Seen by the US as the most dangerous offshoot of al-Qaeda, AQAP opposes both the Houthis and President Hadi.
Islamic State: A Yemeni affiliate of IS has recently emerged, which seeks to eclipse AQAP