Iraqi forces battling their way into Fallujah have repelled a four-hour attack by the Islamic State group in the city's south.

Two officers with the special forces say the attack started at dawn on Tuesday in the Nuaimiya area where Iraqi troops captured almost 85 percent of the ground the previous day, when they first entered Fallujah.

The officers say IS militants used tunnels, deployed snipers and sent six explosives-laden cars to hit the troops but they were destroyed before reaching their targets. The officers spoke on condition of anonymity to discuss the ongoing campaign.

Fallujah, which has been under IS control for over two years, is 65 kilometers (40 miles) west of Baghdad. It's the last major city in western Iraq still under control of the Islamic State group.