The al-Nuri mosque in west Mosul remains outside the reach of Iraqi government forces even as the coalition steps up efforts to reclaim the Old City.
The Iraqi special forces and police have maintained a tight control around the mosque, advancing to within few hundred metres of the mosque over the last few days.
Lieutenant General Raed Shaker Jawdat said, "Federal police forces have imposed full control over the Qadheeb al-Ban area and the al-Malab sports stadium in the western wing of Old Mosul and are besieging militants around the al-Nuri mosque."
The al-Nuri mosque is the same place from where Abu Bakr al-Baghdadi, the leader of the group, declared himself as the leader of the group three years ago.
According to Reuters news agency, helicopters in west Mosul were seen attacking Isis positions on the edge of the Old City, beyond the city train station.
Rapid Response unit, elite forces of the interior ministry are reportedly pushing on the edges of Old City scrambling over garden walls as Isis militants hit them with rocket fire.
Abd al-Amir, a Rapid Response official said on Wednesday, "There are teams going into the Old City since yesterday."
Iraqi forces also took down at least one suspected Isis drone. The jihadists have been allegedly using small commercial drones to spy and drop ammunition on Iraqi military positions.
Meanwhile, thousands of residents of west Mosul have fled the area as many more have been trapped in homes, caught in the battle. Residents also said that they had heard severe sustained gunfire from the Old City.
Iraqi troops have launched a major offensive to gain control of Mosul in October, the last remaining urban stronghold of the jihadists in Iraq. They managed to recapture east Mosul in its entirety in January and began the battle to take west Mosul on 19 February.
On Tuesday, the United Nations chief said that around 307 civilians have been killed and 273 injured in Mosul since 17 February. The agency added that the jihadists were leading residents into buildings that are booby trapped, using them as human shields and shooting those who attempted to flee.