Washington is not prepared to trust the word of the Syrian regime alone that it will rid itself of chemical weapons, US Secretary of State John Kerry said Thursday.

"The words of the Syrian regime in our judgement are simply not enough, which is why we've come here in order to work with the Russians," Kerry told reporters in Geneva ahead of high-stakes talks with his Russian counterpart Sergei Lavrov on the thorny issue of Syria's chemical weapons.

He warned it was also up to Russians to show that they could "deliver on the promise of the moment" after Moscow proposed a plan earlier this week to eliminate Syria's deadly weapons stock.

But Kerry highlighted that the US and Russia still disagreed on who carried out a suspected sarin gas attack near Damascus last month, which Washington says killed 1,400 people.

The attack came in the midst of a brutal civil war which began as a popular uprising to topple President Bashar al-Assad, and which is said to have cost some 110,000 lives in about two and a half years.

"The Russian delegation has put some ideas forward and we're grateful for that. We respect it. And we have prepared our own principles that any plan to accomplish this needs to encompass," Kerry stressed, before a room packed with reporters from around the world.

"Expectations are high. They are high for the United States, perhaps even more so for Russia to deliver on the promise of this moment. This is not a game," he said.

Any deal to bring Syria's chemical weapons stockpile under international control "has to be credible. It has to be timely and implemented in a timely fashion," he said.

Kerry and Lavrov, who have both brought a team of top-level weapons experts with them to pore over the details of the Russian plan, will be making a posh Geneva hotel their operating base until Saturday for the closed-door talks.

The top US diplomat told Lavrov that the United States was "serious as you are, engaging in substantive meaningful negotiations".

"Despite how difficult this is, with the collaboration of our experts, and only with the compliance from the Assad regime, we do believe there is a way to get this done," he said.

"Together we will test the Assad regime's commitment to follow through on its promises".

Lavrov, who addressed the press first, said: "The solution of this problem makes unnecessary any strikes on Syria".

Pending the talks, US President Barack Obama has put on hold plans for limited military strikes against the Syrian regime to disable its chemical weapons capability.

"I am sure that our American partners... are strongly in favour of a peaceful way to regulate chemical weapons in Syria," Lavrov said.

He also told Kerry, speaking through a translator, that "I hope we will achieve all the successes".

But Kerry quipped: "You want me to take your word for it? It's a little early for that".

US must stop 'threats' for weapons plan to work: Assad
Moscow (AFP) Sept 12, 2013 - President Bashar al-Assad said Thursday Syria plans to give up its chemical weapons, and demanded in return that Washington drop threats of military action and stop arming rebels.

In an interview aired by the Rossiya 24 channel as Russia and the United States began talks in Geneva over the plan for Syria to give up its chemical arsenal, Assad said he was ready to comply, but would not do so unilaterally.

"Syria will be sending an appeal to the UN and the Organisation for the Prohibition of Chemical Weapons in a few days, which will have technical documents necessary to sign the agreement," Assad said in remarks translated from Arabic.

The convention would go into effect "one month after signing", at which point "Syria will begin passing data about chemical weapons stockpiles to international organisations," he said.

He warned that Syria will not "carry out these mechanisms unilaterally", saying the United States must call off plans for military intervention.

"It does not mean that Syria will sign the documents, fulfil the terms and that will be all," he said, calling the plan a "two-way process" with Washington required to "stop the politics of threats in relation to Syria."

"When we see that the United States truly desires stability in our region and stops threatening and seeking to invade, as well as stopping arms supplies to terrorists, then we can believe that we can follow through with the necessary processes," he said.

Assad denied that his regime forces were behind the chemical weapons attack that killed 1,400 people including hundreds of children near Damascus and accused Washington of involvement.

"The US threats... to strike Syria were based on allegations of chemical weapons use in Ghouta (a Damascus suburb). These allegations were propagated by the US administration," he said.

Speaking in Damascus in the room where he was interviewed by American television host Charlie Rose just days before, Assad said that Syria was pursuing the chemical disarmament plan because of Russia's proposal, not because of threats of military intervention.

Assad added that he has "trusting relations" with Russia, and Moscow would have to play a key role in the negotiation process.

"We don't have any trust or communication with the United States. Russia is the only state that can carry out this role today," he said.