Moscow, May 18 (IANS): UN Secretary General Ban Ki-moon has expressed regret over the inability of experts, investigating the possible use of chemical weapons in Syria, to visit the country.

"It is regrettable that the team in charge of this investigation was unable to visit Syria and conduct its inquiry on the spot," reported Xinhua citing the UN chief while talking to reporters after meeting Russian foreign minister Sergei Lavrov.

Lavrov, for his part, maintained the Syria crisis could be resolved only via an intra-Syria dialogue without outside interference.

Russia hopes Syria will "remain a sovereign and integrated state", he said, adding that Ban supports the initiative to convene an international conference on Syria that was proposed during a recent visit to Moscow by US Secretary of State John Kerry.

The Syrian government and the opposition have been trading accusations over the use of poison gas in their armed conflict.

Three UN member states, namely Syria, Britain and France, demanded an inquiry into the incident.

The experts' team arrived in Cyprus in April, but waiting for Syria's permission to enter the country.