Aid agencies have voiced concern over the dire humanitarian situation in Mosul, as Iraq's Prime Minister Haider al-Abadi congratulated his troops for driving ISIL out of most of the city.

Iraq's leader arrived in Mosul on Sunday to join Iraqi troops and civilians in celebrating "victories and the eradication of ISIL", which he said they were close to achieving after a nearly nine-month battle.

As the operation nears its end, the intense fighting in the Old City neighbourhood near the Tigris River has taken a heavy toll on the thousands of civilians still trapped in the area.

IN PICTURES: The final push - Retaking Mosul from ISIL

"The humanitarian situation is absolutely dire," said Al Jazeera's Charles Stratford, reporting from Erbil in northern Iraq.

"The level of destruction in the Old City is almost total," he said. "Virtually every single building is either completely or partially reduced to rubble."

According to the Iraqi military, about 15,000 civilians are still in the area of the Old City, with many of them being used as human shields by ISIL (the Islamic State of Iraq and the Levant, also known as ISIS).

The Iraqi military forces are having to check everyone for suicide vests as they leave.

'Massive crisis'

The Iraqi Ministry of Displacement and Migration said that 750,000 have been displaced since the offensive on western Mosul began in February.

Michael Boyce, humanitarian policy adviser from Oxfam in Iraq, said the battle for Mosul has already been a massive crisis, displacing about a million people, and that it will take a long time before life can resume to normal in the city.

He said that the last pocket of the city that has been under attack for the past few weeks is extremely dense to move around in, with a high risk of civilians being killed.

"A lot of people are stuck inside the city with very little access to food, water and medical care," Boyce told Al Jazeera from Erbil. "They have literally been through hell."

Amira Abd El-Khalek, public information officer for UNHCR, told Al Jazeera that while victory against ISIL may be near, the humanitarian situation is not ending any time soon.

As the Iraqi forces make their final push, approximately half of the population of the city is still displaced, the Norwegian Refugee Council (NRC) said.

Tens of thousands of people are likely to return to the city in the near future, placing pressure on the Iraqi government and the international community to begin rebuilding immediately.

It is thought that it will cost more than a billion dollars to repair Mosul's basic infrastructure - more than twice the initial estimate.

Long-term reconstruction will cost several billions as all parts of the city have been damaged in some way.

"People from every ethnic, religious and socioeconomic group in Iraq have suffered as a result of this conflict," said Heidi Diedrich, the NRC's country director.

"It is the responsibility of the international community now to help them rebuild their country and repair the divisions that helped to create the conflict in the first place."