DAMASCUS, April 21 (Xinhua) -- The fact-finding mission of the Organization for the Prohibition of Chemical Weapons (OPCW) entered Damascus's Douma Saturday to look into allegations of chemical weapons use.

The OPCW said in a statement that its experts visited one of the sites in Douma to collect samples for analysis in connection with the allegations of chemical weapons use in Douma on April 7.

The OPCW will evaluate the situation and consider steps including another possible visit to Douma, according to the statement.

It added that the collected samples will be transported to the OPCW laboratories in Rijswijk, the Netherlands for analysis.

This comes as the UN security team entered Douma on Friday to assess the security situation before the visit of the OPCW experts after a previous attempt that ended with the security team returning to Damascus after coming under small arms fire.

The arrival of the OPCW team came after the Syrian government invited the OPCW to investigate the April 7 incident, when the rebels and activists accused the Syrian forces of using chlorine gas in an attack on Douma.

The Syrian government denied the allegations, saying the rebels and their foreign backers were fabricating events to attract foreign military action.

On April 14, the U.S., France and Britain launched a series of missile strikes on Syrian positions over the allegations, and the OPCW team arrived on the same day after the strikes were over.

On Saturday, Syria's Assistant Foreign Minister Ayman Sussan said that investigating the chemical weapons allegations in Douma will expose the lies of the Western countries.

In an interview with Xinhua, Sussan said it was the Syrian government who invited the inspection experts of the OPCW to look into the allegations about the use of chlorine gas in the battles in Douma on April 7 ahead of the withdrawal of the rebels and their families to northern Syria.

"The Syrian government has declared in its invitation letter (to the OPCW), and after the arrival of the (inspection) team, it will fully cooperate and offer all facilitations for the inspection team to carry out its mission," he said.

He added that this "will be of a great interest for us because when the investigation team conducts its work it will expose the lies of the Western allegations and the accusations they have made about the alleged attack in Douma."

In the interview on Saturday, the Syrian official said "the OPCW team in Damascus has held several meetings with the Syrian government, and met with a number of witnesses from inside Douma, including locals, doctors or the medical cadres working in hospitals."

Meanwhile, Sussan slammed the U.S. and its Western allies for overstepping their boundaries by making their allegations and attacks on Syrian positions ahead of the international investigation into the chemical weapons' allegations.

"If they are saying that chemical weapons were used in Ghouta, and if U.S. or France and Britain really wanted to know the truth, they should have provided appropriate conditions for the OPCW to carry out its mission," he said.

He stressed that the Western countries will not stop making allegations and claims because they want to thwart the work of any organization.

The official, meanwhile, said that the goal behind U.S.-led missile strike ahead of the arrival of the investigation team was to hinder the work of the OPCW mission.

"The U.S.-led strike aimed to hinder the work of the inspection mission and the West wanted that because the work of the mission will expose their lies," he said.

He added that "the Western powers thought that the strike on Syria would push the Syrian government to react by preventing the mission from entering Douma."

Unlike the Western stance, Sussan said, the Syrian government respects the international legitimacy and the work of international organizations and promises cooperation with the investigation team.

Sussan stressed that the Western countries know very well that when Syria joined the Chemical Weapons Convention in 2013, it gave up all of its chemical stockpiles.

He charged the Western powers over repeated use of this pretext, adding that the U.S.-led Western alliance was attempting to prolong and complicate the Syrian crisis, preventing the situation from getting better.