The head of the U.N. agency overseeing Syria's chemical weapons destruction says the last remaining eight percent is in a dangerous and inaccessible area.
Sigrid Kaag told reporters after a closed-door Security Council briefing that 16 barrels are all that is left before 100 percent of Syria's stockpile is destroyed.
But she said those barrels are in an area too dangerous to enter because of security problems.
Kaag said full access is critical to ensure Syria meets the June 30 deadline for ridding itself of all chemical weapons. She said the "clock is ticking."
Meanwhile, the head of Syria's main opposition group, Ahmad Jarba, said his talks Thursday in Washington with Secretary of State John Kerry and other top officials will bear fruit for the Syrian people.
Jarba said Syrians are looking to the United States to help them end the suffering.
The United States this week recognized Jarba's Syrian National Coalition as a diplomatic foreign mission.
Secretary of State Kerry said the coalition is a moderate opposition group committed to protecting the rights of all the Syrian people.
"We have obviously an important meeting today with the Syrian opposition coalition and I am very pleased to welcome to the department someone who understands better than anybody the stakes in the struggle in Syria and the fight against extremism," he said. "President Jarba and I have met many times, we have had difficult moments in this journey but we are committed to do our part to support the moderate opposition in its efforts to provide a legitimate voice to the aspirations and hopes of the Syrian people. His coalition, Syrian opposition coalition that he has built is an inclusive and moderate institution committed to the Syrian people and to the protection of all people, all minorities, all rights within Syria. The Syrian opposition coalition has given voice to all Syrians who had been oppressed by the regime for decades."
On Thursday militant Syrian rebels claimed responsibility for blowing up the 150-year-old Carlton Hotel in the historic old city of Aleppo.
The rebels planted bombs in tunnels under the building, completely destroying it. Syrian government forces had been using the old hotel as a base.
The Syrian Observatory for Human Rights says the explosion killed 14 soldiers.
The hotel was located across the street from the Citadel of Aleppo, a 13th-century structure that the United Nations cultural agency describes as a "remarkable example" of military architecture in the region.
Aleppo's old city is a UNESCO World Heritage Site that has been caught in the middle of Syria's civil war. UNESCO placed Aleppo on its listed of endangered historic sites last year. It says the civil war has damaged many of the city's historical sites.