The United Nations-brokered Yemen peace talks are continuing on the fourth day in Kuwait, but with government and Houthi rebel delegations far from reaching an agreement to end the conflict.

The delegations resumed the negotiations on Sunday, but an hour into the talks, "it was obvious for the UN special envoy [Ismail Ould Cheikh Ahmed] that the talks were going nowhere", said Al Jazeera's Hashem Ahelbarra, reporting from Kuwait City.

"There has been no progress here because of huge differences. The envoy had to suspend the session.

"The Houthis later said they are in consultation with their leaders in Yemen about whether to return to the talks or pack up and leave."

The Houthis and the forces loyal to President Abd-Rabbu Mansour Hadi have observed a fragile ceasefire since April 11.

However, the two sides differ on how to move forwards.

"The Houthis say they are willing to negotiate a settlement but they are the ones who have the upper hand therefore they have to have a bigger say in the government," our correspondent said.

"The government says the Houthis used force to seize power so they are the ones who should be held responsible.

"They have to hand over their weapons and pull out from the main cities. Then the talks can start."

The Houthis are demanding an immediate halt to air strikes that the Arab coalition has been carrying out since March last year in support of Hadi.

READ MORE: Life on hold in war-shattered Sanaa

The government delegation said a ceasefire should include opening safe passages to all besieged areas and releasing political prisoners, as well as those abducted, as part of confidence-building measures.

The negotiations in Kuwait, termed "constructive" by Ould Cheikh Ahmed, opened late on Thursday after the delayed arrival of representatives of the Houthi rebels and their allies - forces loyal to Ali Abdullah Saleh, the deposed Yemeni president.

Ground offensive

Against this backdrop of stalled peace negotiations, fighter jets have targeted the al-Qaeda-held port city of Mukalla and killed 30 fighters, residents said.

The Saudi-led coalition has stepped up an offensive to reclaim parts of the south from the control of Al-Qaeda in the Arabian Peninsula (AQAP).

Sunday's air strikes were carried out in coordination with a ground offensive in territory further west, a Yemeni military official said.

"The liberation of Mukalla from the hands of the al-Qaeda terrorist organisation has begun," Ahmed Saeed Bin Breik, the governor, said in a statement.

Local officials said dozens of armoured vehicles and hundreds of troops had assembled in Ramah, about 70km north of Mukalla, in preparation for a ground push.

Nearly 6,200 people have died in the war, which has focused mostly around the Houthi-controlled centre and north, while a security vacuum has spread in the south.