Russian Embassy spokesman Mikhail Sobolev said it would bring a group of 15 Syrians who they claim were filmed in "staged videos" of the alleged attack to a meeting at the OPCW on Thursday, US Time. The Syrian government has denied the allegations and called it fake news. Their entry into the town was delayed by security fears.
The watchdog is not mandated to apportion blame for the attack.
A spokesperson for the Russian mission said the Russian and Syrian representatives would hold a news briefing for members of the organization on April 26 where they would speak about the alleged Douma incident.
The Russian Defense Ministry also showed missile fragments, saying they represent evidence disproving claims by US President Donald Trump and various US military officials, who boasted that all of the 105 missiles fired on Syria reached their targets. Russian Federation has previously claimed that only 71 of 103 missiles launched by the coalition made it past Syria's antiquated air defenses.
Russian Federation will supply Syria with new air defense systems, the RIA Novosti news agency said Wednesday, quoting General Sergei Rudskoy, chief of the Main Operations Directorate of the General Staff.
The US Department of Defense has seen no verifiable proof to support Russian claims of having in its possession intact Tomahawk missiles captured in Syria, department spokesperson Eric Pahon told Sputnik on Wednesday.
He also claimed that United States missiles were captured and sent to Moscow so they could improve Russia's own weapons systems. The West blames Bashar al-Assad and Russian Federation for the attack.More news: Liverpool boss Klopp fears long-term Oxlade-Chamberlain injury
Tensions between regional foes Iran and Israel has intensified in recent weeks over the Islamic Republic's military footprint in Syria, which shares a border with Israel.
An estimated 450,000 people have been killed in fighting in Syria since Assad's government cracked down on demonstrations calling for his ouster in 2011.
The Syrian civil war has been a bloody one.
With fighting still raging and the northern rebel-held province of Idlib in danger of becoming a new crisis zone, European Union foreign policy chief Federica Mogherini urged Russia, Iran and Turkey to use their influence in Damascus, saying they have a "special responsibility" to establish a cease-fire and to press Assad to return to the negotiating table.
"Russian specialists will continue educating Syrian military personnel and will also provide assistance in the mastery of new means of anti-aircraft defense, the deployment of which will be implemented in the near future", Sergei Rudskoy, head of the operations directorate at Russia's General Staff said, according to state news agency RIA Novosti.
Associated Press writers Mike Corder in The Hague, Josef Federman in Jerusalem and Lorne Cook in Brussels contributed.