The provincial governor said the army and militia fighters captured part of the northern district of Qadisiya, while in the south of the Tigris river city a security officer said another force made a rapid push towards the centre.

"The forces entered Tikrit general hospital," an official at the main military operation command centre said. "There is heavy fighting going on near the presidential palaces, next to the hospital complex” Reuters reports.

Allied Iraqi forces entered the city through its northern Qadisiyya neighborhood, where authorities quickly established a supply line to reinforce troops, Salahuddin police Brig. Kheyon Rasheed told the state-run Iraqiyya television.

A local official in Iraq's Salahuddin province also confirmed that Iraqi troops and the militias made it into Qadisiyya. He spoke on condition of anonymity as he was not authorized to brief journalists, AP reports.

The pro-government forces have taken control of al-Alam, a strategic town on the eastern outskirts of Tikrit, and inched closer to the centre of Saddam hometown and former government installations west of the Tigris River, now held by ISIS.

“The forces want to hold the Friday prayers in the centre of Salahuddin,” said Dr Hisham al-Hashimi, who advises the Iraqi government on ISIS, referring to the province whose administrative capital is Tikrit.

The offensive is the largest against the terrorist group since it conquered large areas of the country, including Mosul and Tikrit, in a lightning advance last summer.

ISIS warns people of Mosul not to leave city

A local source in Nineveh province stated to “Iraqi news”, that the ISIS group warned the people of Mosul not to leave the city using loudspeakers, threatening whoever plans to get out to confiscate their property.

The source said “Vehicles belonging to ISIS wandered Mosul’s neighborhoods and warned its residents through loudspeakers not to leave,” explaining that, “Residents were threatened that anyone to leave Mosul would be considered “an apostate” and their property would be confiscated.”Similar warnings were sent through mosques loudspeakers.

But in another part of the country, ISIS Attacks Iraq's Ramadi with 7 Car Bombs.

The ISIS terrorists group launched a coordinated attack on government-held areas of the western Iraqi city of Ramadi on today, involving seven almost simultaneous suicide car bombs, police said.

At least 10 people were killed and 30 wounded in the attack, according to initial reports by police and hospital sources in the city, capital of Anbar province.