US Secretary of State John Kerry and his Russian counterpart Sergei Lavrov were to discuss a time line for eventually destroying Syria's chemical weapons stockpile in a second day of talks in Geneva Friday, diplomats said dpa reported.
The men need to work out differences between the US and Russia on how to rid Syria of its chemical weapons after failing to agree on several points in a first day of talks, the sources said, speaking on condition of anonymity.
The talks could run into the weekend, they added.
As Kerry and Lavrov started their meetings Thursday evening, the United Nations confirmed in New York that Syria had applied to join the Chemical Weapons Convention, the treaty that obliges its members to give up such weapons.
The US wants the chemical disarmament plan to be accompanied by a threat of punitive measures, which would be contained in a UN Security Council resolution, in case al-Assad does not follow through on his promises, the diplomats said.
However, Russia opposes such a resolution, they said.
Syrian President Bashar al-Assad told Russian state television Thursday that he would not disarm unless the United States stopped threatening to attack his country.
Kerry stressed the need to maintain a military option in a meeting with the Syria envoy of the UN and Arab League, Lakhdar Brahimi, in Geneva Thursday, diplomatic sources said.