By Michelle Nichols and Louis Charbonneau
UNITED NATIONS, Feb 27 (Reuters) - There were two attempted attacks on Syrian convoys transporting chemical weapons late last month, Syrian authorities told the international mission overseeing the removal and destruction of its toxic arsenal, according to a U.N. report on Thursday.
The monthly report to the U.N. Security Council of the joint mission of the United Nations and the Organization for the Prohibition of Chemical Weapons said the attempted attacks were on Jan. 27. It gave no details on the location of the convoys.
"In addition, Syrian authorities indicated that ongoing military activities rendered two sites inaccessible during most of the reporting period," the five-page report said.
This delayed "in-country destruction of the final quantities of isopropanol, preventing some activities to consolidate chemical material into a reduced number of locations, and preventing the physical verification of chemical material prior to movement on 27 January 2014."
Isopropanol is one of two key ingredients for sarin.
President Bashar al-Assad agreed to destroy his chemical weapons following global outrage over a sarin gas attack in August, which was the world's deadliest chemical attack in 25 years. It sparked a U.S. threat of military strikes that was averted after Assad pledged to give up his chemical arms.
But the Syrian government, locked in a three-year-old war with rebels seeking to overthrow Assad, failed to meet the Feb. 5 OPCW deadline to move all of its declared chemical substances and precursors - some 1,300 tonnes - out of the country.
Syria has now proposed a new timetable to remove its chemical weapons by late April, diplomats said on Wednesday.
The report said: "The elimination of the chemical weapons programme of the Syrian Arab Republic stands at a critical juncture."
"While progress has been attained under challenging circumstances, it is clear the Syrian Arab Republic must further intensify and accelerate its efforts towards the full elimination of its chemical weapons programme," it said.
Under the OPCW schedule, all Syria's declared chemical weapons must be destroyed by June 30. Most of the chemicals are supposed to be transported to the port of Latakia, where they will be shipped out of the country.
The United States has sent the MV Cape Ray, a ship outfitted with special equipment to neutralize the worst of Syria's chemicals at sea, and says it will need 90 days to complete the destruction.
"Measurable progress has been made over the last months in the destruction of critical equipment and special features at a number of chemical weapons production facilities, as well as unfilled chemical munitions," the report said. "As a result, the production, mixing and filling capabilities of the Syrian Arab Republic have been rendered inoperable."
The deal for Syria to give up its chemical weapons, brokered by the United States and Russia, was enshrined in a U.N. Security Council resolution in September.
The resolution does not authorize automatic punitive action in the form of military strikes or sanctions if Syria does not comply. At Russia's insistence, the resolution makes clear a second council decision would be needed for that.
Russia has made clear, however, it would not support the use of force against Assad's government, a close ally.
(Reporting by Michelle Nichols; editing by Gunna Dickson)