Syria Damascus April 2013
A destroyed car is pictured near a damaged building after an April blast at Marjeh Square in Damascus. Reuters

The United Nations on Friday said it has reached an agreement with Bashar al-Assad's government in Syria regarding an inquiry into the alleged use of chemical weapons in the country’s two-year-old civil war.

The agreement was reached after two U.N. envoys went to Damascus and held talks with Syria’s deputy prime minister, foreign minister and the vice foreign minister, on Wednesday and Thursday.

“The discussions were thorough and productive and led to an agreement on the way forward,” the U.N. said in a brief statement, without elaborating whether its investigators will be allowed into Syria.

Ake Sellstrom, head of the U.N. chemical weapons investigation team, and Angela Kane, chief of the UN Office of Disarmament Affairs, were to report to U.N. Secretary-General Ban Ki-moon on the trip, Agence France-Presse, or the AFP, reported.

Both Assad’s government and the Syria’s opposition forces have been accusing each other of using chemical weapons in the 28-month-old conflict.

Ban, who said the U.N. has received reports of 13 incidents of alleged chemical attacks in the Syrian conflict, has demanded unrestricted access to investigate all alleged chemical attacks, including those reported in Homs and Damascus.

However, Damascus has so far refused to allow the U.N. inspectors to conduct investigations in its territory and has asked U.N. experts to probe only one of the alleged chemical attacks -- the March 19 attack at Khan al-Assal in Aleppo province -- where the Assad government and its ally Russia claim that opposition forces have used chemical weapons.

Opposition forces and the U.S. have accused the Assad regime of using chemical weapons and other weapons of mass destruction. In June, the U.S. said it has evidence that Syrian government forces used chemical weapons, such as sarin gas, against opposition forces, while the White House added that there was no "no reliable, corroborated reporting to indicate that the opposition in Syria has acquired or used chemical weapons," according to a CNN report.

Syria is believed to have huge stockpile of chemical weapons -- including mustard gas – which the U.S and its allies fear could reach Lebanese militant Hezbollah or fall into the hands al-Qaeda militants.