Violations of a UN-brokered ceasefire in Yemen are decreasing as monitors spread out around the war-ravaged country, the Saudi-led coalition said on Friday as peace talks resumed in Kuwait.

The joint committees of rebel and loyalist army representatives are in the field and "are mostly operating", supervised by Saudi members of the coalition, Brigadier General Ahmed Assiri told AFP.

"Our observations tell us that day by day the number of violations keeps decreasing," he said.

The ceasefire began on April 11 to pave the way for the talks aimed at ending 13 months of fighting between Iran-backed Houthi rebels, their allies loyal to former president Ali Abdullah Saleh and government forces backed by air strikes and other support from the Saudi-led Arab alliance.

The Houthis seized Yemen's capital Sanaa in September 2014 and then moved on to other areas.

Peace negotiations had been due to start last Monday, but rebel delegates stayed away in protest at alleged Saudi violations of the truce.

They arrived in Kuwait late on Thursday to begin the talks following UN assurances that the ceasefire would be respected.

The truce has dramatically reduced violence but fighting continues on several fronts as each side blames the other for truce breaches.

Clashes continued overnight Thursday on the outskirts of the southwestern city of Taez and in the northern Jawf province, military sources said.

"Taez is a very difficult city, but I think today is better than yesterday or two days before," Assiri said, adding that the largest monitoring team is there.

The teams, with an average of four representatives from each side, were set up for several provinces under agreements signed by the rebels, army and Saudi coalition in the kingdom's Dhahran South near the Yemen border, just before the ceasefire took effect.

"They have the task to deal with any violation of the ceasefire and to try to fix it on the spot," Assiri said, adding that "it wasn't an easy task" for the Saudi side to bring the combatants together.

"But day by day we build trust between them and I think today they are understanding each other better."

Assiri said that if violations cannot be resolved "on the ground", the coalition reserves the right to strike.

At the moment it is only flying reconnaissance missions, he said.

Analysts say that both the Houthis and the Saudis appear to want a way out of the war.