UNITED NATIONS, April 10 (Xinhua) -- United Nations (UN) Secretary-General Antonio Guterres on Tuesday called for an investigation of the latest allegations of chemical weapons use in Douma, Syria.

"The seriousness of the recent allegations requires a thorough investigation using impartial, independent and professional expertise," said Guterres in a statement.

The statement was released in Boao in China's southern island province of Hainan where the secretary-general is attending the Boao Forum for Asia annual conference.

"In that regard, I reaffirm my full support for the Organization for the Prohibition of Chemical Weapons (OPCW) and its Fact-Finding Mission in undertaking the required investigation into these allegations," he said.

"The Fact-Finding Mission should be granted full access, without any restrictions or impediments to perform its activities," Guterres added.

The Syrian Foreign Ministry said Tuesday that it has sent UN an invitation for a fact-finding mission to investigate the allegations of chemical weapons use in Damascus' eastern district of Douma, state news agency SANA reported.

The ministry said Syria is keen to cooperate with the OPCW "to reveal the truth behind the allegations, which are prompted by some Western powers to justify their aggressive intentions to serve their political goals," the ministry said.

On Saturday, activists said the Syrian government used chlorine gas while bombing Douma, the last rebel-held area in the Eastern Ghouta countryside of Damascus.

The Syrian government rejected the claims, denying being in possession of such weapons.

The norms against chemical weapons must be upheld, said the secretary-general, appealing for the unity of the Security Council on this issue. He also encouraged the council to redouble its efforts to agree on a dedicated mechanism for accountability.

The Fact-Finding Mission of the OPCW has no power to attribute accountability.

In his statement, Guterres expressed outrage at the reports of the use of chemical weapons in Syria.

"I reiterate my strong condemnation of the use of chemical weapons against the civilian population," he said. "Any confirmed use of chemical weapons, by any party to the conflict and under any circumstances, is abhorrent and a clear violation of international law."