MOSCOW/WASHINGTON (REUTERS) - Russian President Vladimir Putin said on Thursday he could not be 100 per cent certain a United States-Russian plan for the destruction of Syrian chemical arms would be carried out successfully, but he saw reason to hope it would.

US Secretary of State John Kerry said it was essential the deal reached last Saturday be enforced and that the United Nations (UN) Security Council be willing to act on it next week, when the UN General Assembly holds its annual meeting in New York.

"The Security Council must be prepared to act next week," Mr Kerry told reporters in Washington. "It is vital for the international community to stand up and speak out in the strongest possible terms about the importance of enforcible action to rid the world of Syria's chemical weapons."

Mr Putin told a gathering of journalists and Russia experts in the Russian town of Valdai that he could not be 100 per cent certain the plan for the destruction of Syria's chemical weapons would succeed.

"But everything we have seen so far in recent days gives us confidence that this will happen," he said, adding, "I hope so."

Russia and the United States brokered the deal to put Syrian President Bashar al-Assad's chemical arms stockpiles under international control to avoid possible US military strikes that Washington said would be intended to punish Mr Assad for a poison gas attack last month.

Under the US-Russian deal, Mr Assad must account for his chemical weapon stockpiles within a week and see them destroyed by the middle of next year.

The five permanent members of the UN Security Council - the US, Britain, France, Russia and China - have been discussing a draft resolution this week that Western powers hope will make the deal legally binding.

But Russia, a key ally of Mr Assad, is unhappy with the draft's references to possible punitive measures against Syria under Article 7 of the UN charter, which talks about UN authorisation for sanctions and military force.

Diplomats say the resolution could come to a vote as early as this weekend or next week.

ASSAD SAYS DISPOSAL COMPLEX, EXPENSIVE

Mr Assad said on Wednesday his government was willing to get rid of its chemical weapons but it would be a very complicated operation that would take about a year and cost about US$1 billion (S$1.27 billion).

"If the American administration is ready to pay this money and take the responsibility of bringing toxic materials to the United States, why don't they do it?" Mr Assad said in an interview with Fox News.

Mr Assad again denied his forces were responsible for a chemical weapons attack in Ghouta, outside Damascus, on Aug 21.

Mr Putin also reiterated Russia's contention that the attack was staged by opponents of Mr Assad.

The US says the attack killed more than 1,400 people, including more than 400 children.

UN chemical investigators confirmed on Monday the use of sarin in a long-awaited report that the US, Britain and France said proved government forces were responsible.

Logistics as to how the deal to destroy the chemical weapons would be implemented have been murky.

Russia and the US are the only countries with industrial-scale capacity to handle mustard, VX, sarin or cyanide-armed munitions, but the import of chemical weapons is banned under US law.

Russia has been destroying its own Soviet-era chemical weapons in line with an agreement with the US and has seven facilities for the destruction of chemical weapons, according to information on Russian Munitions Agency website.

But Russian Defence Minister Sergei Shoigu said on Thursday that Russia had no current plans to destroy Syrian chemical weapons on its territory.

Asked whether Russia had such plans, Mr Shoigu told Interfax news agency: "No. A decision needs to be taken for this."

"We have factories for the destruction of chemical weapons, but there is a big difference between 'ready' and 'willing'."

In a speech on Thursday, the head of Nato welcomed the US-Russian agreement and said individual Nato nations may agree to help implement the deal, but the 28-nation alliance itself was unlikely to play a role.

Speaking in Brussels, Nato Secretary-General Anders Fogh Rasmussen also said it was essential for keeping momentum in the diplomatic and political process that the military option remained on the table.

The violence that has cost more than 100,000 lives in Syria in the past two and a half years continued on Thursday.

Near the Turkish frontier, Al-Qaeda-linked fighters battled a rival Syrian rebel group for a second day after the militant Islamists stormed a nearby town and prompted Turkey to shut a border crossing.

Elsewhere, a roadside bomb killed at least 14 members of Mr Assad's minority Alawite sect in the central Syrian province of Homs, a Syrian opposition monitoring group said.