A top UN official says the United Nations has been told of 13 alleged chemical weapons attacks in Syria.
Robert Serry, envoy on the Middle East peace process, told the Security Council on July 23 that UN Secretary-General Ban Ki-moon remained "gravely concerned" about reports of the use of chemical arms in the 28-month-old conflict.
Serry spoke as Ake Sellstrom, the head of a UN chemical-weapons investigation, and the UN disarmament chief, Angela Kane, arrived in Beirut ahead of a visit to Damascus on July 24.
It was not immediately clear when they would travel to Damascus. Their trip is at the invitation of the Syrian government.
Sellstrom's team has not yet been allowed into Syria due to disagreements over how much access they will have.
Sellstrom and Kane are due to discuss with Syrian officials access to sites where the arms are said to have been used.
Damascus insists that UN investigators only travel to the town of Khan al-Assal, where it alleges rebels used chemical weapons in March.
The UN says they should also be allowed to visit the site of an alleged government chemical-weapons attack.
Both sides in the conflict deny using chemical weapons.
Based on reporting by AFP and Reuters