Islamic State jihadists have made important advances in Iraq despite US-led air strikes, Washington's envoy to the US-led coalition fighting the group warned Wednesday.

It was clear the IS group "has made substantial gains in Iraq" and it will take time to build up local forces that could defeat them in Syria and Iraq, John Allen, a retired four-star US general, told reporters.

The Iraqi government and Kurdish forces have halted or pushed back IS militants in some places, including around Mosul dam, but the group has "tactical momentum" in other areas, Allen said.

Although the United States and its allies were carrying out air raids in both Syria and Iraq, Allen acknowledged the international coalition was most concerned with the situation in Iraq.

There, IS fighters have seized much of the western Anbar province and are closing in on the region west of the capital Baghdad.

"The emergency in Iraq right now in Iraq is foremost in our thinking," Allen said, admitting that it was too early to say which side has the upper hand.

"I'd be careful about assigning a winner -- winner or a loser," said Allen, the former commander of NATO forces in Afghanistan.

Speaking after a tour of the Middle East in which Allen spoke to coalition partners and Iraqi leaders, the presidential envoy emphasized that military power alone would not be enough to defeat the IS group -- a point often made by the White House.

Allen said "the key and the main takeaway from this trip was that we all agree that while the military side is important to the outcome, it is not sufficient in and of itself."

At the moment the plan was "to take those steps that are necessary, with the forces that we have available and the air power that we have at our fingertips" to buy time to train and arm Iraqi security forces.

The goal was to give Iraq's new Prime Minister Haidar al-Abadi "the opportunity to build a stable government that is inclusive."

US officials have repeatedly urged Baghdad to reach out to Iraq's alienated Sunni population and blame the Shiite-led government for sowing resentment that was exploited by the jihadists.

Pentagon officials have said privately that Turkey is ready to grant access to some of its air bases to assist the coalition campaign against the IS militants, but details of the deal remain unclear.

Allen shed no light on what kind of arrangement Turkey had agreed to but denied Ankara was a reluctant partner in the fight.

He said "they want to understand how they'll fit into the program and how ultimately the coalition would operate out of Turkey."

A team drawn from the US military's Central Command and European command was in Turkey "talking about operational details," he said.

Battles rage to hold back IS as Obama consults leaders
Mursitpinar, Turkey (AFP) Oct 15, 2014 - Kurdish and Iraqi forces fought to hold back advancing jihadists on the Syria-Turkey border and near Baghdad on Wednesday as Washington pushed to rally its allies against the Islamic State group.

In the Syrian town of Kobane on the Turkish border, Kurdish fighters backed by a flurry of US-led air strikes were reported to have stopped IS fighters from gaining more ground and had even recaptured some positions.

US Central Command said American aircraft struck the jihadists with 18 raids near Kobane on Tuesday and Wednesday, hitting 16 buildings occupied by the group.

In Iraq, pro-government forces beat back an hours-long jihadist attack on a key city west of Baghdad, while reinforcements reached a strategic town threatened by militants.

But US military officials warned on Tuesday that IS had the "tactical momentum" and President Barack Obama was to hold a video conference with the leaders of Britain, France, Germany and Italy to discuss the IS threat.

Obama told military chiefs from more than 20 allies on Tuesday they are facing a "long-term campaign" against IS.

"There are not quick fixes involved. We're still at the early stages," Obama said after the talks in Washington.

"As with any military effort, there will be days of progress and there are going to be periods of setback," he added.

Obama's call with European leaders was to start at 1500 GMT and last about an hour, with the Ebola epidemic and peace efforts in Ukraine also on the agenda.

Obama has expressed special concern for Kobane, which has become a symbolic battleground in the fight against IS, and about halting the IS advance in Iraq's western Anbar province.

- Clashes for Kobane HQ -

Fresh US-led strikes could be seen hitting IS positions in Kobane on Wednesday, an AFP reporter across the border in Turkey said.

A monitoring group said fighting was concentrated on the former Kurdish military headquarters in northern Kobane which IS seized on Friday.

The Britain-based Syrian Observatory for Human Rights said Kurdish forces had retaken two IS positions near the headquarters and pushed the jihadists from several streets to its west, but IS fighters appeared to remain in control of about half the town.

Turkey, a NATO member, has stationed troops, tanks and artillery along the border -- in some cases only a few hundred yards from the fighting -- but has not intervened.

It also has yet to allow US jets to mount attacks from its territory and complicated issues Tuesday by bombing Kurdish rebel targets in the southeast of the country.

In Iraq, security personnel and tribesmen repelled a seven-hour assault on the city of Ramadi, the capital of the embattled Anbar province.

IS jihadists attacked from three directions after hitting the city with mortar fire, police Captain Tahsin al-Dulaimi said.

The town of Amriyat al-Fallujah, a key area closer to the capital that is one of the last parts of Anbar still holding out against the jihadists, also received reinforcements from the Iraqi army on Wednesday.

Local forces warned on Tuesday the town was in serious danger, with its police chief saying that if Amriyat falls "the battle will move to the gates of Baghdad" and the holy Shiite city of Karbala.

Its fall would increase the danger to Baghdad, but IS fighters would still have to capture a significant stretch of government-controlled territory before reaching the capital.

Government forces have suffered a string of bruising setbacks in Anbar in recent weeks, prompting some officials to warn that the entire province, which borders Jordan, Saudi Arabia and Baghdad province, could fall within days.

- Rising support for US troops -

Some officials in Anbar have argued anything short of an intervention by US ground forces would lead to Anbar falling into jihadist hands.

Washington has ruled out sending troops back to Iraq to fight IS, but a poll published Wednesday showed a rising number of Americans think US ground forces are needed.

Forty-one percent of those surveyed believe the fight should include both air strikes and ground troops, up from 34 percent in September, according to the NBC News-Wall Street Journal poll.

IS has seized control of large parts of Syria and Iraq, declaring a "caliphate" in June and imposing its harsh interpretation of Islamic sharia law.

The group has committed widespread atrocities, including attacks on civilians, mass executions, torture and forcing women and children into slavery -- a practice US Secretary of State John Kerry denounced on Tuesday as "abhorrent".