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.

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

- Rebels demand talks -

"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.

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".

On Wednesday, the coalition had launched new raids on Huthis who overran a major base of pro-Hadi troops in Taez.

Northeast of Sanaa, as well as in Taez, overnight raids targeted positions held by the Huthis and rebel troops loyal to former president Ali Abdullah Saleh.

On Thursday, they targeted Yarim in Ibb province, where warplanes hit an old university building used as a rebel headquarters, residents said.

- IS claims attack -

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.

IS claimed its first attack in Yemen on March 20 -- multiple suicide bombings targeting Huthis at Shiite mosques in Sanaa that killed 142 people and wounded more than 350.

Al-Qaeda has traditionally been the dominant jihadist group in Yemen and has exploited the growing turmoil to expand in the largely lawless southeast.

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.

In Aden, warplanes hit rebel positions and clashes raged between pro- and anti-Hadi forces, witnesses said.

The World Health Organization says that at least 944 people have been killed in Yemen since March 19.

UN Secretary General Ban Ki-moon appealed for an end to the fighting and offered the "diplomatic facilities through which we can resolve this issue through dialogue".

Ban said he had proposed a successor to UN envoy Jamal Benomar, who resigned last week after reportedly losing support among Gulf countries.

Human Rights Watch said a coalition air strike on an Oxfam warehouse on April 18 in the northern rebel stronghold of Saada appeared to have violated the laws of war.

The coalition has not commented on the incident.

The Red Cross warned of a "catastrophic" humanitarian situation, with fuel supplies at "zero levels" and an acute shortage of food leading to soaring prices.

The Bill & Melinda Gates Foundation announced it has approved funding of $800,000 for the International Medical Corps "to deliver emergency relief" across Yemen.

In Nairobi, meanwhile, Somali Prime Minister Omar Abdirashid Ali Sharmarke warned that the Yemen conflict poses dangers across the Gulf of Aden where an influx of refugees is stretching scarce resources and Al-Qaeda is eager for support.