BAGHDAD -- Iraq's influential Shiite cleric Muqtada al-Sadr has threatened to boycott the upcoming provincial elections, urging instead followers to join a "reform revolution."

Al-Sadr spoke to thousands at an anti-government protest on Friday in Baghdad, calling for continued peaceful rallies.

He says Iraqis who love their country and hate corruption, regardless of ideology, support the "reform revolution." The remarks reflect continued power struggles in Baghdad even Iraqi forces battle the Islamic State group in Mosul.

Al-Sadr first took up the mantle of reform over a year ago, when escalating protests occasionally turned violent, breaching Baghdad's highly fortified Green Zone, home to the government and many foreign embassies.

Iraq is to hold local elections later this year -- the first elections since IS overran nearly a third of the country in 2014.