The Organisation for the Prohibition of Chemical Weapons has said that almost half of Syria's declared chemical stockpile has now been removed from the country.
The stockpile includes Syria's entire stock of lethal mustard gas.
In a joint statement, the OPCW and the United Nations said that 45.6% of the chemicals had been removed from Syria's Latakia port for destruction outside the country.
Syria agreed to give up its chemical weapons programme last year in a deal with Russia and the United States.
The deadline was agreed as part of a plan to avert US-backed military strikes.
However, it is several months behind schedule and risks missing a 30 June deadline for the chemicals to be destroyed.
It has asked to be given until 27 April to complete the removal of the chemicals, which would put the mission two-and-a-half months behind schedule.
Syrian authorities, battling a three-year uprising and insurgency against President Bashar al-Assad, blame security problems for the delays in bringing the chemicals to Latakia.
The joint UN-OPCW mission said the delivery of the latest two consignments to vessels off Latakia means that 29.5% of the "Priority 1" chemicals, considered the most dangerous, and 82.6% of "Priority 2" chemicals have been removed.