Two United Nations officials who arrived in Beirut on Tuesday were scheduled to travel to Damascus the following day for discussions on the alleged use of chemical weapons in the Syrian civil war, dpa reported.
Swedish chemical weapons expert and head of a UN investigative team Ake Sellstrom and disarmament official Angela Kane were to discuss the framework that would allow a UN team to begin its work in Syria.
On June 11, the UN accepted an invitation by the regime of Syrian President Bashar al-Assad to investigate the use of chemical weapons in Khan al-Assal in the northern province of Aleppo in March.
Meanwhile, the head of the main Syrian opposition alliance, Ahmed al-Jarba, is to hold informal talks on Friday in New York with UN Security Council members on the situation in Syria.
The British ambassador to the UN, Mark Lyall Grant, said the meeting will allow "frank and informal exchanges ... on key issues relating to the Syrian conflict."
Grant said the issues include preparations for the Geneva II conference, humanitarian access, human rights, refugees and protection of civilians in Syria.
At least 93,000 people have been killed in the Syrian civil war, according to the UN.
Russia alleged this month that its experts had collected samples of sarin nerve gas used by the opposition in Syria on March 19, and provided an 80-page analysis to the UN, China, France, the United States and Britain.
France, the US and Britain have given the United Nations what they claim is evidence of chemical weapons use by the Syrian government.
Al-Jarba was elected head of the Syrian National Council earlier this month. The 115-member coalition groups key opposition figures living in exile and inside Syria.
It has, however, been mired in divisions, mainly over proposals to negotiate an end to the conflict with al-Assad's regime.