Elite Iraqi troops backed by US jets battled jihadists just south of Baghdad Wednesday as Washington devised a strategy for expanded operations against the Islamic State group.

President Barack Obama prepared to meet with US commanders to decide how to turn the tide on the most powerful and brutal jihadist group in recent history while keeping a promise not to drag America into another military quagmire.

The White House scrambled to play down a suggestion by the top US officer that deploying ground forces was an option but expanded air strikes were already turning up the heat on the Islamic State (IS) group.

According to Iraqi military and tribal leaders, US jets struck three IS targets in an area south of Baghdad which has been dubbed the "triangle of death", killing at least four militants.

A leader of the Janabi tribe in the flashpoint region of Jurf al-Sakhr, less than 50 kilometres (30 miles) south of Baghdad, said Iraqi soldiers had fought IS militants until early Wednesday.

"The main focus was an area of Jurf al-Sakhr called Fadhiliya. They fought deep into the night but the Iraqi army was not able to enter the place," a leader from the local Janabi tribe told AFP.

The US military issued a statement late Tuesday that spoke of three air strikes southwest of Baghdad but did not specify where.

The Jurf al-Sakhr region is seen as a key area because it sits on the Euphrates River between the major Sunni insurgent bastion of Fallujah, west of Baghdad, and the country's most revered Shiite holy sites south of the capital.

The tribal leader and an army lieutenant said the push was led by the Golden Brigade, which is widely recognised as the best force in the country.

Critics say it may be the only credible fighting force in what is sometimes derided as "a checkpoint army".

The brigade, which spearheaded an offensive the retake the country's largest dam north of Mosul last month, has been hopping from one key frontline to another.

The US administration has said that its strategy in Iraq would involve helping to revamp an army it had not finished training when the eight-year occupation ended in 2011.

General Martin Dempsey, chairman of the US Joint Chiefs of Staff, said on Tuesday that US military advisers could "provide close-combat advising".

But the White House insisted the idea of US troops in battle was a "purely hypothetical scenario."

The more than 160 air strikes launched by the US since August 8 have achieved some results, apparently forcing top IS leaders to cross the border back into neighbouring Syria.

On Tuesday, Kurdish peshmerga forces -- which have been receiving military equipment from Washington and some of its Western allies -- retook seven Christian villages east of Mosul with US air support.

The villages had been emptied of their population during an IS offensive in August.

According to a senior Kurdish leader, Roj Nuri Shaways, a top IS military commander known as Abu Abdullah was killed in the fighting.

Calls have been mounting in Iraq for Washington to expand its air support to Sunni tribesmen fighting the jihadists, particularly in the town of Dhuluiyah, north of Baghdad.

On Wednesday, Obama is to sit down with General Lloyd Austin, chief of US Central Command at his Florida headquarters.

The president "plans to discuss the plan for building an international coalition to degrade and destroy (IS)," White House spokesman Josh Earnest said.

British and French planes have already started surveillance missions over Iraq.

In Washington, Defence Secretary Chuck Hagel told US lawmakers Tuesday that plans were being laid to hit targets in Syria, where the IS group is holding Western hostages and has a stronghold in the city of Raqa.

"This plan includes targeted actions against ISIL safe havens in Syria, including its command and control, logistics capabilities, and infrastructure," Hagel told the Senate Armed Services Committee.

Over the past month, IS sparked global outrage by releasing video footage of two US reporters and a British aid worker being beheaded. It also warned it would take the battle to America and its allies.

A US court on Tuesday indicted a Yemeni-born US man for allegedly providing material support to IS by recruiting members for jihad in Syria.

French lawmakers the same day approved a new anti-terror bill aimed at preventing potential jihadists from travelling to Iraq or Syria.