UN tells Syrian government to move faster

Syria's government must do more to present its ideas about a political transition and not merely talk about principles of peacemaking, UN mediator Staffan de Mistura has said after a fifth day of peace talks.

The end of a week of talks in Geneva came as Syria neared the three-week mark in its "cessation of hostilities", a temporary truce in the five-year-old civil war that has largely held but was marred by "some incidents" on Friday, he said.

"We are in a hurry," he told reporters after what he called an "intense" day and meetings with Syria's government delegation and the main opposition, the High Negotiations Committee.

De Mistura said he had given both sides weekend homework so negotiations could speed up on Monday, and during the second week of discussions he would go deeper into the issue of a political transition.

He had told the government delegation they could talk about procedures if they wished, but it was impossible to avoid dealing with the substance, he said.

"In the end, people in Syria don't need procedure, they need reality and they expect that from us."

Syria's war has killed more than 250,000 people and caused the world's worst refugee crisis, with more than half the pre-war population displaced.

Next week he aimed to build "a minimum common platform" to better understand how to approach a post-war transition, which is the core issue to be tackled at the next round of talks in April, he said.

"We are already aiming very clearly for that."

De Mistura said he had been impressed by the depth of the engagement in the process by the HNC, including substantive points on its vision of a peaceful transition.

Syrian President Bashar al-Assad has rejected opposition demands he give up power as a precondition for lasting peace.