Syrian President Bashar al-Assad says he is committed to a plan to destroy his country's chemical weapons but warns it could take about a year and cost $US1 billion.
In an interview with the United States television channel Fox News, Mr Assad says it is a technically complicated operation that could damage the environment: "And it needs a lot of money, some estimates (say) about a billion," the BBC reported.
Mr Assad again denied claims that his forces were responsible for a deadly chemical attack in the Ghouta area near Damascus on 21 August.
The Syria disarmament plan was unveiled by the US and Russia last weekend. The West wants the deal enshrined in a UN resolution backed by the threat of military force but Russia objects.
Mr Assad's comments came shortly after a senior Russian diplomat said Damascus would fulfil its commitment to eliminate its chemical weapons by mid-2014, reports the BBC.
After talks in Syria on Wednesday, Deputy Foreign Minister Sergei Ryabkov said Mr Assad was "very serious" about the disarmament plan.
Mr Ryabkov also said that Syrian officials had handed him "material evidence" that showed the rebels were involved in the sarin attack last month, contradicting claims by the US that the regime was responsible.
And the Russian diplomat criticised the United Nations for being "one-sided" in its recent report on the attack - a claim the UN denied.
The report - prepared for UN weapons experts after a visit to Syria - did not apportion blame for the 21 August attack.
New border fight
The BBC reports In a separate development, fierce fighting has been reported between two rebel groups in the north of Syria.
The fighting reportedly began when jihadists from the al-Qaeda-linked group, the Islamic State of Iraq and the Levant (Isis), and fighters from the Western-backed Free Syrian Army (FSA) clashed in the town of Azaz, near the Turkish border.
Activists said on Thursday morning that Isis fighters had overrun the town.
This is believed to be one of the biggest confrontations so far between the jihadists and the FSA, the BBC reports.
German chemical exports
Meanwhile Germany's Chancellor Angela Merkel has said in an interview on German television that chemicals exported to Syria which were capable of being used to make poison gas were used for civilian purposes.
The German government, responding to a request from a member of parliament, said 137 tonnes of two substances capable of being used to make the poison gas, Sarin, were exported to Syria between 2002 and 2006.
But she added that officials were still trying to ascertain what use was made of chemicals exported after 2006 and before May 2011, when Germany imposed strict controls on exports to Syria, the BBC reports.
More than 100,000 people have been killed since Syria's civil war began in early 2011, according to the UN.
Millions have fled the country and millions more have been left homeless.