MOSCOW - The UN experts' possible return to The Hague for sample delivering should not prevent further investigation over alleged chemical weapons use in Syria, the Russian Foreign Ministry said Thursday.

"In particular, the inspections must be carried out, besides a Damascus suburb, at three other sites previously agreed between the Syrian authorities and the UN Secretariat on Aug. 13," the ministry' s spokesman Alexander Lukashevich said in an online comment.

The diplomat said the UN experts must implement their mandate and submit a report to the UN Security Council.

The UN investigation team was originally scheduled to spend up to 14 days with a possible extension probing the chemical weapons cases in the northern Khan al-Assal town and other locations.

According to Lukashevich, Moscow insists on all-inclusive discussions in the UNSC of the alleged use of chemical weapons in Syria, while demanded that a report prepared by Russian experts also be taken into account.

On Wednesday, the UN Secretary General Ban Ki-moon called upon all parties in Syria to extend their full cooperation to the UN investigation on the alleged use of chemical weapons in Syria.

The Syrian government and rebels blamed each other for a purported chemical-weapons attack in Khan al-Assal on March 19 that killed at least 25 people and wounded 130 others.

Besides, on Aug. 21, the Syrian opposition claimed that some 1,300 people were killed in a chemical weapon attack carried out by the government army on militant strongholds in the suburbs of Damascus.

The Syrian government has strongly denied the accusation.