MOSUL, Iraq (AP) — Islamic State militants have launched an overnight attack against Iraqi security forces in southeastern Mosul, a day after the troops advanced deeper into the city.

Iraqi Army Sgt. Maj. Hakim Saranbii told The Associated Press on Wednesday the attack "inflicted heavy losses" without providing further details. Iraqi Defense Ministry officials in Bagdad didn't immediately comment.

On Tuesday, Iraq's army rolled into the southeastern neighborhood of al-Salam, taking a hospital before meeting stiff resistance from IS militants. Convoys of dozens of armored Iraqi special forces and army Humvees could be seen moving into the southeastern neighborhood Wednesday morning.

Backed the U.S.-led international coalition, Iraqi government troops and paramilitary forces launched a campaign in October to dislodge IS from Mosul, Iraq's second-largest city and IS's last major urban bastion in the country.