Iran says a U.S. plans to form a new border security force in Syria will cause more instability and "add flames of fire" in the war-torn country.

The Iranian Foreign Ministry spokesman Bahram Ghasemi says the U.S. plan for a new Kurdish-led force will further complicate the conflict in Syria and is a "blatant intervention" in Syria's internal affairs.

Ghasemi's comments were carried by Iran's official news agency IRNA on Tuesday.

The new force has already been criticized by Turkey, Russia and the Syrian government.

The U.S.-led coalition says the force, expected to reach 30,000 in the next several years, is a key element of its strategy to prevent the resurgence of the Islamic State group in Syria and would be deployed along Syria's border with Turkey and Iraq.