Saudi-led naval forces imposed a blockade on Yemen's ports as coalition airstrikes on Monday repelled an advance on the southern port city of Aden by Shiite rebels and forces loyal to a former president.
The move to block ports appeared aimed at preventing the rebels, known as Houthis, from rearming, and comes after the coalition achieved full control of the skies and bombed a number of rebel-held airports. The rebels are supported by Iran, but both Iran and the Houthis deny Tehran has armed them.
Saudi Brig. Gen. Ahmed Asiri, the coalition spokesman, told reporters in Riyadh that naval forces are blocking the movement of ships to prevent weapons and fighters from entering or leaving Yemen. He said they had not yet intercepted anything.
The airstrikes have targeted at least nine of Yemen's 21 provinces and have prevented the Houthis from reaching Aden, the former capital of the once-independent south, where President Abed Rabbo Mansour Hadi declared a temporary capital after fleeing rebel-controlled Sanaa.
Hadi, who was a close U.S. ally against a powerful local al-Qaida affiliate, fled the country last week, but remains Yemen's internationally recognized leader. The U.S. has provided support to the Saudi-led coalition striking Yemen but is not carrying out direct military action.
The conflict marks a major escalation in the regional struggle for influence between Saudi Arabia and Iran, which also back rival sides in Syria's civil war. Sunni Arab leaders unveiled plans Sunday to form a joint military intervention force, which could raise tensions further.
Asiri said much of the airstrikes on Sunday and Monday focused on slowing the Houthi advance on Aden. He said the Houthis tried to fire ballistic missiles on Monday but that they malfunctioned. Warplanes then struck the force that had tried to launch them, he said.
The Houthis' TV network said the coalition bombed a displaced persons camp in the northern rebel stronghold of Saada, killing 40 people, including women and children.
However, witnesses told The Associated Press that the camp — used to house displaced people from an earlier conflict that ended five years ago — is now occupied by Houthi forces and that most of those killed were fighters.
When asked about the allegations, Asiri said the Houthi fighters operate among civilians. It was not immediately possible to resolve the conflicting accounts.
The Houthis and security forces loyal to former President Ali Abdullah Saleh had earlier launched a fresh offensive against Aden, shelling it and battling local militias, but were pushed back by at least two airstrikes, security officials said. Saleh stepped down following a 2011 Arab Spring uprising, but has maintained wide influence through loyalists in the security forces.
Yemeni security officials say the combined force of Houthis and Saleh loyalists is positioned about 30 kilometers (19 miles) east of Aden, near the southern city of Zinjibar. The rebels have used artillery to target pro-Hadi militias known as the Popular Committees. Battles are also underway near the airport.
The account of the fighting was confirmed by four military and security officials, who spoke on condition of anonymity because they were not authorized to brief reporters.
Emboldened by the airstrikes, the Popular Committees have largely held their ground in Aden province and still control most of the city.
The death toll from the ground fighting in Aden since Thursday has reached 86, with some 600 people wounded, according to Abdel-Nasser al-Wali, head of a local medical center.
A series of airstrikes meanwhile shook the capital Sanaa overnight and early Monday morning. The strikes have targeted militants, jets, air defense systems and Scud missile launch pads that could threaten Saudi Arabia.
The Houthis said airstrikes also targeted camps in Fag Atan, where Scud missiles are stored.
Later in the day, the officials said aircraft struck areas near the presidential palace in Sanaa and several other sites across the city, sending balls of fire into the sky, shattering windows and shaking houses.
The daily airstrikes have bred a climate of anxiety and uncertainty in Sanaa. Schools are shuttered, residents are staying indoors, and hundreds have fled to the safety of nearby villages.
In the southern city of Baihan in Shabwa province, airstrikes mistakenly struck a gathering of anti-Houthi tribesmen, causing a number of deaths and injuries, a tribal leader said on condition of anonymity, citing security concerns. It was not clear how many were killed.
In the western coastal city of Hodeida, medical officials said one person was killed and others wounded when the Houthis dispersed a demonstration denouncing their takeover and demanding the release of detainees.
Fighting meanwhile intensified in the southern city of al-Dhale, where the Houthis and Saleh loyalists have been trying to open up a corridor to Aden. They have met fierce resistance there, and the city is currently split between supporters and opponents of the rebels.
Since the air campaign began, the Houthis have arrested some 140 foreign nationals on suspicion that they are providing the Saudis with intelligence on the locations of army barracks, radars and air defense positions, according to the rebel-controlled Interior Ministry.