The White House on Wednesday expressed concern about reports saying Syrian government forces used chemical weapons in an attack on civilians and called on the United Nations to probe the incident.

"The United States is deeply concerned by reports that hundreds of Syrian civilians have been killed in an attack by Syrian government forces, including by the use of chemical weapons, near Damascus earlier today," said White House spokesman Josh Earnest in a statement.

Earnest said the U.S. is formally requesting that the United Nations urgently investigate this new allegation, and has also called for urgent consultations in the UN Security Council to discuss these allegations. The U.S. has also urged the Syrian government to provide immediate access to the UN investigative team, which is currently in Syria.

"If the Syrian government has nothing to hide and is truly committed to an impartial and credible investigation of chemical weapons use in Syria, it will facilitate the UN team's immediate and unfettered access to this site," said the spokesman, who also called for all Syrian parties to provide immediate access to all sites of importance to the investigation and to ensure security for the UN investigative team.