MOSCOW — A U.N. team is returning to Syria on Wednesday to look more deeply into the use of chemical weapons there.

A Russian diplomat revealed the planned trip Tuesday, adding that Moscow remains doubtful the government has used such weapons against its people. A U.N. spokesman subsequently confirmed that the mission would go back to Syria Wednesday to finish its investigation of allegations of chemical weapons’ use, including a report of a March 19 incident at Khan al-Asal.

The United States and Russia agreed to a plan Sept. 14 for Syria to turn over its chemical arsenal, averting an imminent U.S. strike meant to retaliate for the use of chemical weapons against its citizens. But Russia has remained critical and suspicious of U.S. intentions regarding Syria and reiterated its contention that a sarin attack carried out Aug. 21 near Damascus was more likely the work of rebels.

“Even though they agreed to a compromise on chemical weapons, U.S. representatives keep insisting that the Syrian regime, as they call it, is responsible,” Russian Deputy Foreign Minister Sergei Ryabkov said Tuesday. “Without presenting any irrefutable evidence, they are saying all the time that the plans to ‘punish’ Damascus, even through military intervention, remain in force.”

The U.N. team, led by Swedish scientist Ake Sellstrom, had been planning to visit three other sites where attacks had been reported, but after investigating the incident near Damascus left the country because of the prospect of U.S. air strikes.

"We hope that they will go to the places that they had no time to inspect during their previous visits for some reasons," said Ryabkov, who discussed the issue with Russia’s lower house of parliament Tuesday. “We will continue tackling this issue, including with the help of the additional data that we are currently receiving from the Syrian side."

The U.N. report on the Aug. 21 attack did not assign blame, but Western governments have said the evidence makes it clear the sarin came from forces under Syrian President Bashar al-Assad.

“Our position is that this report requires serious and scrupulous analysis,” Ryabkov said, “while the conclusions that were publicly announced as soon as the report was presented were too hasty."

President Obama, in a speech to the United Nations General Assembly on Tuesday morning, is focusing attention on a resolution that would authorize some manner of penalty for Syria if it refuses to give up its chemical weapons.

Russia has been opposed to any action against Syria, though it has suggested it might change its mind if it found the Syrian government was indeed guilty of chemical weapons’ use.

"Regrettably,” Ryabkov said, “I have to admit that our contacts with Americans are not very smooth and, generally speaking, are not moving in the direction in which they should be moving today."