Geneva (AFP) - Syria's government may be on board for the UN-brokered review of its constitution, but it will sink the Geneva talks opening Wednesday before agreeing anything that compromises its authority, experts have said.

Opposition negotiators and some analysts also fear that Damascus will use its participation as a bargaining chip to normalise relations with the West, and eventually get sanctions lifted.

UN envoy for Syria Geir Pedersen welcomed as a "sign of hope" the creation of the committee tasked with amending the constitution for a nation battered by eight years of war.

UN Secretary General Antonio Guterres agreed. The committee would be taking "the first step on the political path out of the tragedy of the Syrian conflict", he said in a statement.

The committee's 150 members -- including government, opposition and civil society delegates -- start work on Wednesday.

But some experts argue that it will merely offer yet another opportunity for President Bashar al-Assad's government to appear open to UN-backed diplomacy without giving anything away.

Assad "has nothing to lose," at the talks, Aaron Lund of the Century Foundation told AFP.

"If the process turns unpleasant for some reason, it's no big deal. He'll just make up some technical reason to stall it," he said.

- 'New' constitution? -

Once all the delegates have gathered for the opening ceremony at the UN, 45 of them will begin working on a draft constitution.

Pedersen said the aim would be to reach consensus on all issues.

Where that was not possible, changes would only be made with a 75-percent majority vote in the committee to avoid having any one side dictate the process.

But the prospects of consensus appears remote.

While the opposition has called for an entirely new text, Syrian Foreign Minister Walid Muallem argued that amending even one article of the current charter would amount to a "new constitution".

Damascus has also insisted that the process have no deadline.

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The Assad government may agree to a few amendments, International Crisis Group senior analyst Sam Heller told AFP -- but a "completely rewritten" constitution appeared impossible.

Damascus only agreed to join the Geneva meeting at the urging of its Russian allies, he argued.

While Moscow pursued Syrian diplomacy outside of the UN-umbrella, it always maintained that a solution to the conflict had to earn the UN stamp of approval.

Constitutional review is a central part of the UN-led effort to end the war in Syria, which has killed more than 370,000 people and forced millions to flee their homes since 2011.

Security Council resolution 2254, which defines the UN push for peace, also calls for UN-supervised elections in Syria.

- 'Dirty little deals' -

While Assad's forces have steadily made gains against the opposition, his cash-strapped government is still hit by EU and US sanctions. It desperately needs funds to rebuild the war-ravaged country.

Russia has repeatedly called for the international community to unlock Syrian redevelopment funds.

Opposition negotiators warned last month that Assad could use its participation at the constitutional review as a "card" to press its case for financial aid.

"If it turns out there's an opportunity to use this (constitutional) forum to unlock new opportunities and normalise ties with the international community, (Assad) will do that," Lund said.

"What the constitutional committee can do, at best, is to put a gloss of international legitimacy on whatever dirty little deals may be hashed out behind the scenes."