Warplanes from the Saudi-led coalition pounded rebel positions across Yemen on Thursday as air raids intensified amid attempts to revive UN-proposed talks in Switzerland, witnesses said.

Jets targeted positions held by Shiite Huthi rebels and allied forces loyal to former president Ali Abdullah Saleh in the city of Taez.

Military sources in Aden said coalition warplanes also struck rebel forces on the outskirts of the port city, in support of pro-government fighters from the southern Popular Resistance.

Rebels bombed western neighbourhoods of Aden which house people who have fled other parts of the city, witnesses said.

At least 15 people, including civilians and southern fighters, have been killed in Aden since Wednesday, according to local health chief Al-Khader Laswar. More than 100 have been wounded.

Overnight strikes pounded rebels in the city, the scene of fierce fighting since the insurgents advanced on Aden where President Abedrabbo Mansour Hadi took refuge after fleeing rebel house arrest in Sanaa in February.

Hadi is now in Saudi Arabia which with nine other Arab countries put together a coalition that began air strikes in Yemen on March 26, aiming to restore him to power.

Warplanes also targeted arms depots at the Hamza military base in Ibb province and air raids also hit a Huthi base in Dhamar province, witnesses said.

Thursday's raids followed a night of intensive air strikes against rebels in Taez and coastguard positions in Hodeida in western Yemen, as well as Huthi positions in their northern stronghold of Saada.

Talks proposed by the United Nations in Geneva were postponed days before they were due to start on May 28 after the UN failed to convince the warring parties to attend.

UN envoy to Yemen Ismail Ould Cheikh Ahmed has now tentatively set June 14 for talks between all parties to the conflict.

He told the UN Security Council on Wednesday that Yemen's government is ready to go to Geneva but that the rebels have yet to confirm they will attend.

The talks would be aimed at securing a ceasefire, agreeing on a withdrawal plan for the Huthis and stepping up deliveries of humanitarian aid, according to diplomats who attended the closed-door briefing.

More than 2,000 people have been killed in the Yemen conflict since late March.