The United Nations has accepted the Syrian government's invitation for a visit by two senior UN officials for talks on the purported use of chemical weapons in the country's bloody civil war, a UN spokesman said Wednesday.

The offer of talks was made to Swedish scientist Ake Sellstrom, named by the United Nations to investigate the claims, and Angela Kane, UN High Representative for Disarmament.

Sellstrom and Kane have accepted the invitation "with a view to completing the consultations on the modalities of cooperation required for the proper, safe and efficient conduct of the UN mission to investigate allegations of the use of chemical weapons in Syria," said Martin Nesirky, spokesman for the UN chief.

Nesirky did not specify a date for the visit.

He also noted Sellstrom had met Wednesday with UN Secretary General Ban Ki-moon.

In announcing the invitation, Syrian ambassador to the UN Bashar Jaafari rejected a suggestion that Damascus was attempting to shift the scope and purpose of the UN investigation, declining to "anticipate" the outcome of the talks.

President Bashar al-Assad's government insists that the UN should focus on an incident attributed to Syrian opposition forces on March 23 at Khan al-Assal near the northern city of Aleppo.

According to the UN, Damascus has barred its investigators from examining claims made by Britain and France of chemical weapons use by regime forces at Khan al-Assal and Homs in December last year.

The divergence in UN and Syrian positions has stymied the fact-finding mission so far.

As soon as the invitation was issued, the UN emphasized that wanted "access for the investigating team without further delay and without any conditions."