"The Syrian authorities and Russian troops will provide conditions to travel to the areas of the alleged incident for them to familiarise themselves with the situation", he said.
In 2017, Trump launched a cruise missile strike against a Syrian air base after a sarin attack the United Nations later pinned on President Bashar al-Assad.
White House security adviser Tom Bossert refused to rule out U.S. military action in response to the alleged chemical strike.
According to the officials, the Russians started jamming smaller US drones several weeks ago after a series of suspected chemical weapons attacks on civilians in rebel-held eastern Ghouta.
United States Ambassador to the United Nations Nikki Haley addresses the United Nations Security Council meeting on Syria at the U.N. headquarters in NY, U.S., April 9, 2018.
The French representative at the UN Security Council said poison gas had deliberately been used as it could seep down to the basements. Any riposte would most likely be in coordination with the United States, government aides said.
Israel rarely acknowledges strikes in Syria but has said that, as a matter of policy, they aim to thwart the entrenchment of Iranian forces or arms transfers to Hezbollah.
France has repeatedly said that evidence of chemical weapons use in Syria could prompt military action and said Sunday it would "do its duty" following the latest allegations. We have no choice.
A joint military operation, possibly with France in the lead, could send a message of worldwide unity.
The council would ask UN Secretary-General Antonio Guterres to outline within 30 days the operation of the panel "based on the principles of impartiality, independence and professionalism", according to the draft text obtained by AFP.
The Assad government has denied the latest attack, backed by its allies, Russian Federation and Iran.
Nebenzia alleged that the anti-government forces had chemical weapons and could stage an attack.
US Vice President Mike Pence will fill in for Trump on the tour.
Robert Wood, U.S. ambassador to the Conference on Disarmament, says "Syria has neither the global credibility nor any moral authority" to lead the forum, "given what they have done to their own people with use of chemical weapons".
Acting Secretary of State John Sullivan spoke by phone Monday with British Foreign Secretary Boris Johnson.