A powerful Iraqi Shiite cleric says the additional 560 U.S. troops to be sent to Iraq to upgrade an air base recently retaken from the Islamic State group would be a "target" for his supporters.

Muqtada al-Sadr's threat came in response to a question from a supporter about the deployment, announced last week by U.S. Defense Secretary Ash Carter.

Al-Sadr wrote on his official website late Sunday that "they are a target for us," without elaborating.

Al-Sadr's supporters fought major battles against American troops during the 2003-11 U.S. intervention in Iraq and have been fighting IS in the two years since the Sunni militants swept across much of northern and western Iraq.

In recent months, al-Sadr has been campaigning for reform and an end to government corruption.