WASHINGTON (Reuters) - The U.S. State Department on Friday cautioned Russia and Syria against tampering with the site of a suspected chemical attack in Syria’s Aleppo last month, adding that it had information indicating that Russian and Syrian personnel were involved in what it called a tear gas attack.

“We caution Russia and the regime against tampering with the suspected attack site and urge them to secure the safety of impartial, independent inspectors so that those responsible can be held accountable,” a State Department spokesman said in a statement.