A spokesman for the OPCW, the UN-backed arms watchdog that is overseeing the removal of President Bashar al-Assad's chemical weapons arsenal, said: "We have received part of the verification and we expect more."
The OPCW'S Executive Council is due to meet early next week to review Syria's inventory and to agree on implementing the US-Russian deal agreed last week to eliminate the entire arsenal in nine months.
The timetable was set down by US Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov when they agreed a plan to deprive Assad of chemical weapons and so avert US strikes.
The plan set a rough deadline of today for Syria to give a full account of its chemical weapons, with security experts saying it has about 1000 tonnes of mustard gas, VX and sarin - the nerve agent found when hundreds were killed in strikes on rebel-held suburbs on August 21.
One western diplomat warned that if there were gaps in Syria's documentation, "this matter is going to go straight to the Security Council", where enforced compliance would be sought.
The US and its allies said the UN inspectors' report this week left no doubt that Assad's forces were responsible for the killings while the president has blamed rebels.
The Syrian government has sought to join the OPCW after accepting the Russian deal, which solved a dilemma for President Obama, who has found Congress unwilling to support his strike plan.
Once the OPCW executive has voted to follow the Lavrov-Kerry plan in a meeting expected early next week, the Security Council is due to give its endorsement in a rare show of consensus after two years of deadlock over Syria.
Syria's rebels have voiced dismay at the pact and accuse the west of being sidetracked by the chemical weapons issue while Assad's forces use a large conventional arsenal to try to crush the revolt.
Moscow and Washington have said that progress on removing chemical weapons could pave the way for a broader diplomatic effort to end a conflict that has killed well over 100,000 and destabilised the region.
Rising bitterness, especially along sectarian lines, and also a fragmentation into rival camps, particularly on the rebel side, will hamper negotiations.
Yesterday, al Qaeda-linked fighters and a unit of Syrian rebels declared a truce after two days of clashes near the Turkish border that highlight opposition divisions.
Fighters from an al Qaeda affiliate, the Islamic State of Iraq and the Levant (ISIL) fought with the Northern Storm Brigade, a group that controls the border.
While some tensions stem from contrasting ideological outlooks, most rebel-on-rebel fighting is more about control of territory and the spoils of war.
In other parts of Syria, al Qaeda-affiliated forces have enticed rebels to join them.
Hundreds of rebels, including entire brigades, have pledged allegiance to ISIL and its domestic branch the al-Nusra Front in northern and eastern Syria, Islamist sources said yesterday.