BEIRUT: Syria's government and opposition meet Monday for a seventh round of UN-sponsored peace talks in Geneva with little expectation of a breakthrough to end the six-year conflict.

The Geneva process has been increasingly overshadowed by a separate track organized by regime allies Russia and Iran, and rebel backer Turkey.

And on Sunday, a ceasefire brokered by the United States, Russia and Jordan began in southern Syria, the latest agreement reached outside the Geneva framework.

In principle, the new round of negotiations will focus on four so-called "baskets": a new constitution, governance, elections and combating "terrorism".

The last talks had ended in May with little progress towards ending a war that has killed more than 320,000 people since it began in March 2011.

UN Syria envoy Staffan de Mistura said afterwards that "important gaps remain... on major issues," and that time constraints had stymied progress.

Syria's opposition insists that President Bashar al-Assad must step down as part of any political solution to the war, but the government says Assad's fate is not up for discussion.

Still both sides are expected to participate once again, with Yehya al-Aridi, a spokesman for the opposition High Negotiations Committee, telling AFP he had "modest expectations".

UN welcomes ceasefire deal

The Geneva talks began in 2014, and have continued intermittently despite a dearth of results.

Since January, they have been increasingly overshadowed by a separate process held in Astana and organised by Russia, Iran and Turkey.

The three countries agreed in May to set up four "de-escalation zones" in Syria, though they have so far failed to agree details necessary to implement the plan.

Meanwhile, US, Russian and Jordanian officials have agreed a ceasefire in southern Syria that began on Sunday and covers three provinces included in one of the "de-escalation" zones.

De Mistura's deputy Ramzi Ezzedine Ramzi has said the ceasefire deal "helps create a suitable atmosphere for the talks".

"We hope that an agreement will be reached for the other areas that have been discussed as soon as possible and this will lead to significant support for the political process," he added.

Geneva vs. Astana

Syria's opposition fears the Astana talks are a way for regime allies to control the negotiation process.

By attending the Geneva talks, Aridi said, the opposition hoped to preserve the track.

"The goal is to maintain some momentum for a political solution in light of Russia's attempts to divert attention to Astana, which it wants to design and shape as it wishes," he told AFP.

Syria analyst Sam Heller, writing for the Century Foundation think-tank, said the opposition and its backers viewed Geneva as "a chance for smaller tactical wins and a vessel for a possible future deal".

"It's also about keeping an internationally recognized political process shaped by key opposition backers, rather than ceding the negotiating space to the rival Astana negotiations track, over which Russia has presided."

Washington, once a key opposition backer and peace process partner, stepped back from involvement in the diplomatic process after President Donald Trump took office in January.

But its involvement in the south Syria ceasefire raises the prospect it may be re-engaging in a limited fashion.

US Secretary of State Rex Tillerson said American and Russian officials had discussed "other areas in Syria that we can continue to work together on".

And in Washington, a senior State Department official said both countries had a role to play in ending Syria's conflict.

"If there's going to be a resolution of the conflict in Syria, we both need to somehow be involved in it."