MOSUL: Advancing Iraqi troops broke through the militant Islamic State group`s defence lines in an eastern suburb of Mosul on Monday, taking the battle for the insurgents` stronghold into the city limits for the first time, a force commander said.

They made the gain as the US-backed offensive to recapture Mosul the largest military operation in Iraq since the invasion that toppled Saddam Hussein in 2003 after two weeks of fighting to clear surrounding areas of insurgents.

Commanders had warned earlier that the battle for the city, the hardline militants` de facto capital in Iraq, could take weeks and possibly months.Troops of the Iraqi army`s Counter-Terrorism Service (CTS) moved forward on Gogjali, an industrial zone on the eastern outskirts. They then reached Karama district, their first advance into the city itself, an officer said.

`They have entered Mosul,` he said. `They are fighting now in Hay (district) al-Karama.` A correspondent in the village of Bazwaia saw plumes of smoke rising from a built-up area a few kilometres away which a commander said was the result of the clashes in Karama.

A Kurdish peshmerga intelligence source said he received a report saying seven IS militants were killed in the Aden district, adjacent to Karama, and two of their vehicles destroyed. Iraqi statetelevision said there were clashes inside the city between residents and IS fighters.

The fighting ahead is likely to be more difficult as civilians still live there, unlike most villages taken so far by the Iraqi forces which were emptied of their Christian population. Prime Minister Haider al-Abadi, speaking at the Qayyara military airbase south of Mosul, said the Iraqi forces were trying to close off all escape routes for the several thousand IS fighters inside Mosul.

`God willing, we will chop off the snake`s head,` Abadi, wearing military fatigues, told state television. `They have no escape, they either die or surrender`.

The recapture of Mosul wouldmarkthemilitants`effectivedefeat in the Iraqi half of the territory they had seized.

Mosul is still home to 1.5 million residents, making it four of five times bigger than any other city they controlled in both Iraq and Syria.

Hadi al-Amiri,leader of the Badr Organisation, the largest Shia militia fighting with Iraqi government forces, warned on Sunday that `the battle of Mosul will not be a picnic` and could last months.

On Monday, he expressed hope that Mosul would not descend into a protracted and devastating conflict like the four-year-old battle in the Syrian city of Aleppo, where Shia militias are also fighting.-Reuters