Syrian President Bashar al-Assad can take "credit" for moving quickly to eliminate his regime's chemical arms, the United States said Monday, as disarmament experts declared Damascus was being "cooperative".

Speaking in Indonesia, US Secretary of State John Kerry welcomed the start of work to destroy Syria's chemical weapons under the terms of a UN Security Council resolution.

"The process has begun in record time and we are appreciative for the Russian cooperation and obviously for the Syrian compliance," he told reporters after talks with Russian Foreign Minister Sergei Lavrov.

"I think it's extremely significant that yesterday, Sunday, within a week of the resolution being passed, some chemical weapons were being destroyed," Kerry said.

"I think it's a credit to the Assad regime, frankly. It's a good beginning and we welcome a good beginning."

Lavrov added that Russia and the United States hoped to convene an international peace conference next month.

Syria agreed to give up its chemical arsenal under last month's UN resolution, which enshrined an agreement struck between Washington and Moscow aimed at averting US military action.

Under the plan, Syria's chemical weapons production facilities must be destroyed by November 1.

The process is being overseen by a joint team from the United Nations and the Organisation for the Prohibition of Chemical Weapons (OPCW), which arrived in Damascus last Tuesday.

On Sunday, it began overseeing the first work to destroy and disable parts of the weapons arsenal.

"It was an excellent first day; stress on the word first," an official from the UN-OPCW mission told AFP Monday.

"There will be many more days and more milestones and we expect the continued cooperation of all concerned so that we can pass those milestones effectively."

On Sunday, the team said Syrian workers "used cutting torches and angle grinders to destroy or disable a range of items" including "missile warheads, aerial bombs and mixing and filling equipment."

Syria's chemical arsenal, believed to include 1,000 tonnes of the nerve agent sarin, mustard gas and other banned arms at dozens of sites, must be destroyed by mid-2014.

At the Hague, the OPCW said some of its officials were heading back from Damascus after "constructive" talks with "cooperative" Syrian authorities about the operation.

As the operation got under way, Assad admitted in an interview that his government had made "mistakes" in the country's brutal conflict.

But he again denied his forces used chemical weapons in an August 21 attack that killed hundreds of civilians.

The assault led to threats of a US strike and eventually the UN resolution requiring Syria to give up its arsenal.

Later on Monday, UN chief Ban Ki-moon is expected to send a report to the Security Council detailing the logistics of what is considered one of the biggest and most dangerous disarmament operations ever.

On Monday rebels launched a major assault on two key military bases in northwestern Syria, killing 10 soldiers and destroying three tanks in the heaviest fighting the area has seen in months, activists said.

The offensive -- dubbed "The Earthquake" -- was aimed at seizing Wadi Deif and Hamidiyeh, which the insurgents have besieged for almost a year, said the Syrian Observatory for Human Rights.

Wadi Deif, a garrison housing a large quantity of weapons in Idlib province, is located near Hamidiyeh, the last military stronghold in the region still in the hands of Assad's army.

Elsewhere in the country, the army completely reopened the only supply route linking central Syria with the northern city of Aleppo after a year of fierce fighting between the two sides.

At least 115,000 people have been killed since the uprising began in March 2011. Two million have become refugees and millions more have been displaced inside Syria, as entire neighbourhoods in major cities have been reduced to rubble.

Lavrov said Russia and the United States had agreed to push for the convening of a Syria peace conference in Geneva next month.

"We advocate holding the international conference in mid-November," Lavrov told journalists after his talks with Kerry in Indonesia.

"Today we agreed on the steps needed for both the government and the opposition to come to the conference," Lavrov was quoted as saying by the RIA-Novosti news agency.