DAMASCUS — After months of drawn-out negotiations, United Nations officials arrived in Damascus on Sunday to begin their investigation into the purported use of chemical weapons in Syria’s civil war.
The rebels, along with the United States and other Western powers, have accused President Bashar Assad’s regime of carrying out the alleged chemical attacks, while the Syrian government and Russia have blamed the opposition. Nearly six months after the weapons of mass destruction were first allegedly employed on the battlefield, definitive proof remains elusive.
The UN team that arrived in Damascus on Sunday is tasked with determining whether chemical weapons have been used in the conflict, and if so which ones. But the mission’s mandate does not extend to establishing who was responsible for an attack, which has led some observers to question the overall value of the inquiry.
The 20-member UN delegation, led by Swedish chemical weapons expert Ake Sellstrom, checked into a five-star hotel upon arrival in central Damascus. Plainclothes police officers immediately whisked them away from a crush of reporters and cameramen waiting in the lobby.
UN spokesman Martin Nesirky said the team will begin its work on Monday.
The investigators are expected to visit three sites where chemical weapons attacks allegedly occurred: the village of Khan al-Assal just west of the embattled northern city of Aleppo and two other locations that have not been disclosed.
Syria is said to have one of the world’s largest stockpiles of chemical weapons, including mustard gas and the nerve agent sarin. There are concerns that the Assad regime might use them on a large scale, transfer some of them to the Lebanese militant Hezbollah group, or that the chemical agents could fall into the hands of Al Qaeda.
Ahead of the experts’ arrival, Syria’s deputy foreign minister, Faisal Mekdad, said that the government will offer the UN inspectors its full assistance.
‘‘I assure you, on behalf of the Syrian Arab Republic, that we will fully cooperate with this team and provide it with all information we have and all facilities to reach a rational conclusion,’’ he said.
‘‘Our basic target is for this team to find facts on ground, especially about what happened in Khan al-Assal, because we, as a government, do not know about any other cases other than the case where chemical weapons were used by terrorists there,’’ he added. Syria’s government refers to rebels fighting its rule as terrorists.
A spokesman for the Western-backed Syrian opposition’s military wing, Loay al-Mikdad, also welcomed the UN mission but was skeptical about how fruitful the investigation will be.
‘‘We hope that this delegation will be able to reach all areas where unconventional weapons have been used,’’ Mikdad said. ‘‘However, we’re absolutely sure that this regime that has done everything from changing signs with the names of areas to fabricating evidence with past delegations will do the same with this one. Therefore, we doubt they will be able to uncover truthful results.’’
Mikdad said the rebels, if asked, will facilitate a visit by inspectors to opposition-held areas and no restrictions would be placed on their movements.
The Syrian government initially asked the United Nations to investigate an alleged chemical weapons attack on March 19 in Khan al-Assal, which was captured by the rebels last month. The government and rebels blame each other for the purported attack, which killed at least 30 people.
Britain, France, and the United States followed with allegations of chemical weapons use in Homs, Damascus, and elsewhere. UN Middle East envoy Robert Serry told the Security Council last month the United Nations has received 13 reports of alleged chemical weapons use in Syria.
Speaking to the Associated Press, Mekdad insisted that Syria ‘‘will never use chemical weapons against its people.’’
‘‘We said that these weapons were used in Syria, and Syria was the first to inform the United Nations that armed groups used these weapons in Khan al-Assal,’’ the Syrian deputy foreign minister said. ‘‘We had wished that the United Nations had conducted the investigation immediately at the time so the team would not find difficulties gathering evidence.’’
In June, the United States said it had conclusive evidence that Assad’s regime used chemical weapons against opposition forces.