WARDAK/arbil - Kurdish Peshmerga forces launched a fresh attack on Islamic State (IS) forces early on Sunday as part of a campaign to capture Mosul, the militants' de facto capital in Iraq, Kurdish officials said.

The advance began after heavy shelling and air strikes by a United States-led coalition against IS forces, a Reuters correspondent reported from Wardak, 30 km (19 miles) southeast of Mosul.

The militants fought back, firing mortars at the advancing troops and detonating at least two car bombs.

Clouds of black smoke rose from the area and dozens of civilians fled in the direction of the Peshmerga lines, brandishing white flags.

A Peshmerga commander said 11 villages had been taken from the ultra-hardline Sunni militants as the troops headed to Gwer, the target of the operation, 40 km (25 miles)southeast of Mosul.

Repairing the bridge that the militants destroyed in Gwer would allow the Peshmerga to open a new front around Mosul. The bridge crosses the Grand Zab river that flows into the Tigris.

The Iraqi army and the Peshmerga forces of the Kurdish self-rule region are gradually taking up positions around Mosul, 400 km (250 miles) north of Baghdad.

It was from Mosul's Grand Mosque in 2014 that Islamic State leader Abu Bakr al-Baghdadi declared a "caliphate" spanning regions of Iraq and Syria.

Mosul is the largest urban centre under the militants' control, and had a pre-war population of nearly 2 million.

Its fall would mark the effective defeat of Islamic State in Iraq, according to Iraqi Prime Minister Haider al-Abadi, who has said he aims to retake the city this year.

The Iraqi army is trying to advance from the south. In July it captured the Qayyara airfield, 60 km (35 miles) south of Mosul, which will serve as the main staging post for the expected offensive.

Kurdish journalist killed in northern Iraq

An Iraqi Kurdish reporter was killed and another wounded on Sunday during a military operation against the Islamic State group in northern Iraq, officials said.

The incident occurred during an operation launched by the Kurdish peshmerga forces near Mosul, the country's second city and the jihadist organisation's de facto capital in Iraq.

The journalists, working together for Kurdistan TV, were following peshmerga forces involved in the assault which began early Sunday.

The Kurdistan Democratic Party, which owns the channel, announced the death in a statement.

"We deplore the loss... of cameraman Mustafa Said from the Kurdistan TV satellite channel and the injury of correspondent Hayman Nanqli," the KDP media office said in a statement.

It said the incident was caused by a mortar round fired into a village recently retaken by the peshmerga from IS.

Iraq's Journalistic Freedoms Observatory, a press freedom NGO, confirmed the cameraman's death.

A peshmerga commander said the goal of the operation was to secure a part of the Nineveh plain between Mosul and Arbil, the capital of the autonomous Kurdish region.

"A military operation was launched this morning... to recapture 10 villages on the eastern bank of the Khazr river (and) has so far succeeded in recapturing six," Colonel Muwaffaq Zebari told an AFP reporter on the frontline.

He said the ground operation was getting air support from the US-led coalition and was aimed at preventing further IS attacks on an area called Gweyr, about 40 kilometres (25 miles) southeast of Mosul.

A senior officer in the peshmerga, who was speaking on condition of anonymity, said seven members of the Kurdish forces were also killed in the fighting, but no official confirmation was immediately available.

Mosul is the last remaining city controlled by IS in Iraq and the next big military target for the myriad forces battling the jihadists in the country.

The Kurdish advance east of Mosul on Sunday is part of shaping operations that have been taking place on several fronts for weeks.

Federal forces have also been working their way northwards up the Tigris river valley in a bid to set up bases around Mosul and start tightening the noose around IS's last major bastion.

Iraqi Prime Minister Haider al-Abadi has vowed to retake Mosul and rid the country of IS by the end of 2016.

The Peshmerga operation on Sunday "is one of many shaping operations that will also increase pressure on ISIL in and around Mosul," said the Kurdistan Regional Security Council in a statement, using another acronym to refer to IS.

The preparation for the offensive on Mosul "is approaching the final phase," Brett McGurk, the U.S. envoy to the coalition fighting the militant group, said in Baghdad on Thursday.

He said the planning included humanitarian considerations.

Once the fighting intensifies around Mosul, up to one million people could be driven from their homes in northern Iraq, posing "a massive humanitarian problem", the International Committee of the Red Cross said last month.

More than 3.4 million people have already been forced by conflict to leave their homes across Iraq, taking refuge in areas under control of the government or in the Kurdish region.