Iraqi forces battled deep into the devastated historical heart of Mosul and closed in fast on the last pockets of jihadists Sunday, eight months into an epic battle to retake the city.

Three years after overrunning Mosul and making it the de facto Iraqi capital of the "caliphate" they proclaimed, the jihadists only controlled about a square kilometre in the city, commanders said.

Lieutenant Colonel Salam al-Obeidi was speaking to AFP inside the devastated Old City, about 50 metres (yards) from what is left of the Hadba leaning minaret the jihadists blew up four days earlier.

"Sixty-five to 70 percent of the Old City has been liberated, there is less than a square kilometre left to retake," said Obeidi, from the elite Counter-Terrorism Service (CTS) that has spearheaded the assault.

He estimated that only "a few hundred Daesh fighters" were left in the Old City, using an Arabic acronym for IS.

The ornamental brickwork on the base of the 12th century Hadba (Hunchback) minaret, which was Mosul's symbol and one of the most recognisable landmarks in Iraq, was visible in the background.

The cylindrical shaft of the minaret came tumbling down when IS on June 21 detonated explosives the jihadists had rigged to it.

The jihadists simultaneously blew up the nearby Nuri mosque, where Abu Bakr al-Baghdadi gave his first sermon as IS leader in July 2014, his last public appearance to date.

The narrow, windy streets of the Old City, an area packed with heritage treasures covering about three square kilometres on Mosul's west bank of the Tigris, were littered with rubble.

- Stench of bodies -

The fighting has been among the most intense in the three-year-old war against IS.

AFP reporters said the destruction in Old Mosul was extensive, with some buildings still standing but none unscathed.

"We will finish the operation within a few days. The end is going to be very soon, it will take days," Staff Lieutenant-General Abdulwahab al-Saadi, a top CTS commander, told AFP in the Old City.

The jihadists, who have no escape from their last redoubt in the Old City, have mounted a fierce defence using booby traps, mortars, suicide attacks and snipers.

On Sunday the Joint Operations Command coordinating the war against the jihadists said some IS fighters "tried to infiltrate into the Al-Tanak" neighbourhood in west Mosul.

CTS forces surrounded the area, backed by the army and the air force, and "killed many of the IS fighters", a statement said, adding "the situation is now under control".

The massively outnumbered and outgunned group of die-hard jihadists are said to be holding tens of thousands of civilians as human shields.

Iraqi forces launched a perilous assault on the Old City on June 18, eight months into an offensive to retake Mosul, the country's biggest military operation in years.

Hundreds of IS fighters have been killed since the operation started on October 17, hundreds of civilians have also died. More than 800,000 people have had to flee their homes and many are still housed in overcrowded camps.

The part of Mosul that lies east of the Tigris river that divides the city was reconquered by January with limited damage to homes and infrastructure.

Life and business has returned there, despite an administrative vacuum that still needs to be filled, reconstruction projects that have yet to take off and fears that IS sleeper cells could sow fresh chaos.

The west bank, where the Old City is located, has seen extensive destruction however and areas considered among the heritage jewels of the Middle East have been completely levelled.

AFP reporters in the Faruq neighbourhood of the Old City Sunday saw ancient buildings, some of them from the 11th century, reduced to dust.

As the din of mortar, rocket and gun fire echoed only a few blocks away, the stench of putrefying bodies filled streets blocked by mounds of rubble and mangled cars.

The rotting corpses of dead jihadists could be seen but it was still unclear, only hours after the neighbourhood was retaken, how many civilians might also have died under their own collapsed homes.

Source: AFP