SANAA - Saudi-led coalition warplanes launched new strikes in Yemen on Thursday despite a demand by rebels for a complete halt to the raids as a condition for UN-sponsored peace talks.

The regional alliance on Tuesday declared an end to the first phase of its operations against the Iran-backed Huthi rebels and their allies, but vowed to keep hitting them with targeted bombing when necessary.

UN Secretary General Ban Ki-moon meanwhile informed the Security Council that he plans to appoint Mauritanian diplomat Ismail Ould Cheikh Ahmed as his new envoy to Yemen.

The death toll from fighting in Yemen since late March has topped 1,000, the United Nations said Thursday, saying it wanted to quickly send international staff back to the country. Fighting and airstrikes by a Saudi-led coalition “have impacted virtually the entire country,” UN humanitarian coordinator for Yemen Johannes Van Der Klaauw said in a statement. “The toll on civilians has been immense,” he added.

Cheikh Ahmed replaces Morocco’s Jamal Benomar, who resigned last week after losing support from Gulf countries for his mediation efforts.

Saudi Arabia and its Arab allies launched the air war on March 26 in an attempt to restore the authority of President Abedrabbo Mansour Hadi, who was forced to flee abroad last month as the rebels swept across the country. After the end of Operation Decisive Storm, the coalition said the campaign would enter a phase dubbed Operation Renewal of Hope focusing on resuming political talks, aid deliveries and “fighting terrorism”. “The Huthis should be under no illusion that we will use force in order to stop them taking over Yemen by aggressive actions. So that will not change,” Saudi ambassador Adel al-Jubeir told reporters in Washington on Wednesday.

The alliance said it had destroyed the rebels’ missile and air capabilities, but the Huthis and their allies still control the capital Sanaa and swathes of the country while Hadi remains in self-exile in Riyadh.

The rebels on Wednesday called for a complete halt to the air raids so warring parties could return to the negotiating table.

“We demand, after a complete end to the aggression against Yemen and the lifting of the blockade, to resume political dialogue... under the sponsorship of the United Nations,” said spokesman Mohammed Abdulsalam.

The new overnight raids hit rebel positions near Sanaa, around third city Taez and in the central town of Yarim, according to witnesses.

Residents also reported strikes in the southern province of Lahj and near the main southern city of Aden, where clashes between rebels and fighters loyal to Hadi raged on. Three raids also hit rebels in the eastern province of Marib, and other strikes targeted a rebel-held air base at the airport in the western city of Hodeida.

Abdulkhaleq Abdulla, political science professor at the University of the Emirates, said the conditions for an effective ceasefire had not yet been met. “The war is not over,” he said, but “there are several attempts to find a political solution”.

Iranian ships are moving northeast away from Yemen, a US official said on Thursday after a convoy of Iranian cargo ships prompted US concerns that Tehran was sending weapons into the region. The official, speaking on condition of anonymity, called the move a “promising sign” but said the United States would continue to monitor to see if the ships’ course continued.

On Thursday, they targeted Yarim in Ibb province, where warplanes hit an old university building used as a rebel headquarters, residents said. A newly announced division of the Islamic State jihadist group also claimed a bombing in Yarim on Wednesday that it said had killed five rebels. In a message on Twitter, the “Green Brigade” said it had struck a Huthi vehicle. In the southern provinces of Lahj and Daleh, five rebel positions in schools and public buildings were “razed” by air strikes, a pro-Hadi armed committees leader told AFP.

Meanwhile, the United States is concerned a group of Iranian cargo ships may be carrying advanced weapons to Yemen, Defense Secretary Ash Carter said on Wednesday, as he called on Iran to avoid “fanning the flames” of the conflict with arms deliveries.

Asked whether he thought weapons were on board the Iranian ships, Carter said: “We’re certainly concerned about that.”

“And there’s no reason for anybody to be delivering advanced weapons into a situation that’s already gotten way beyond what is reasonable there,” he told a small group of reporters, shortly before landing in California. He did not elaborate.

On Tuesday, President Barack Obama said the United States had warned Iran not to send weapons to Yemen that could be used to threaten shipping traffic in the Gulf.

Washington this week deployed additional warships off Yemen’s coast, partly in response to the convoy of Iranian cargo ships in the Arabian sea.

Carter acknowledged that the movement of the US warships, including the aircraft carrier USS Theodore Roosevelt, gave President Barack Obama “options.” But he declined to say whether the United States might attempt to board the Iranian cargo ships, if needed.

“I’m not going to tell you what the United States is prepared to do. As the president said, we have options,” Carter said.

Saudi Arabia declared an end of the first phase of its campaign on Tuesday after almost a month of air strikes against the Iranian-allied Houthis. But hours later, air strikes and ground fighting resumed and the International Red Cross described the humanitarian situation as “catastrophic”.

A Gulf official told Reuters that the new phase of the Saudi campaign would see a downscaling of military activity by the Saudi-led coalition with no further bombing of fixed military targets.

On the political front, the official said, there was movement toward a dialogue.

Carter lamented the violence but voiced hope for peace efforts, saying the United States had hoped to “get the parties back to the table.”

He said: “We would like to see the parties get back to a political settlement, and get the country back to some decent level of governance and violence to subside. That’s going to take all parties to the conflict to be willing to step back and talk.”