Igor Kirillov, head of Russia's radiological, biological and chemical protection unit, told reporters the roads still had to be de-mined and cleared and would be tested by United Nations security services on Tuesday.
On Monday, Syrian and Russian authorities prevented investigators from the Organisation for the Prohibition of Chemical Weapons (OPCW) from going to the scene, the head of the OPCW said, blocking worldwide efforts to establish what happened and who was to blame.
The claim by the OPCW comes as Russian foreign minister Sergei Lavrov was forced to deny Russia tampered with evidence at the alleged attack site.
The lack of access to Douma has left unanswered questions about the attack.
OPCW director-general Ahmet Uzumcu said Syrian and Russian officials had cited "pending security issues" in keeping its inspectors from reaching Douma.
Igor Kirillov, a Russian chemical weapons protection expert in The Hague, said the team is set to visit the site on Wednesday.
Speaking to the BBC on Tuesday morning (AEST), Mr Lavrov again denied chemical weapons had been used in Douma.
Syria and its ally Russia deny any chemical attack took place, and Russian officials went even further, accusing Britain of staging a "fake" chemical attack.
Russian military police were ready to help protect the OPCW experts on their visit to Douma, said Major General Yuri Yevtushenko of the Russian military's Reconciliation Centre in Syria.
Syrian government forces retook Douma last week, gaining full control over the former rebel-held enclave of Eastern Ghouta, Russian military officials announced at the time.
The announcement came just days after the Douma attack, following which the US, UK and France launched a coordinated missile strike on facilities believed to be used to research, develop and store chemical weapons inside Syria.
The Chemical Weapons Convention outlaws the production or stockpiling of chemical weapons.
Syria is a signatory of the treaty.
"The alleged use of chemical weapons in Syria can not be a justification for military airstrikes in a territory of a sovereign state without the authorisation of the UNSC".
Syria has lived through a seven-year civil war that has killed at least half a million people and created an worldwide refugee crisis. But "strangers entered as we were in a state of chaos and spread a rumour among people there had been a chemical attack, and people became alarmed".
"The Syrian regime has an abhorrent record of using chemical weapons against its own people".
The commander, who spoke on condition of anonymity, attributed the malfunction to "a joint electronic attack" by Israel and the United States targeting the Syrian radar system. Despite polls showing scant support for the move, May said it had been her "responsibility as prime minister to make these decisions", while Macron also defended his move as part of his constitutional powers. It included a visit to the main hospital to which the victims of the alleged chemical attack where taken.
Nikki Haley, US ambassador to the United Nations, has said her country will announce new sanctions on the Russian government in response to its support for Syria's President Bashar al-Assad.