Iraqi military forces have reached the centre of the northern city of Baiji in an effort to break an Islamic State siege of the country's biggest refinery, triggering fierce clashes with the militants, according to an army colonel and a witness.
Separately, contradictory reports emerged over the fate of Abu Bakr al-Baghdadi, leader of the Islamic State (also known as ISIS or ISIL) after US-led air strikes against the group in at least two locations in Iraq on Friday night.
The United States said it had no information to indicate Baghdadi had been hit, but a report on Iraqi state television said he had been wounded.
Baghdadi's fighters seized much of northern Iraq five months ago in a lightning offensive which also saw them capture the city of Baiji and surround its oil refinery, halting production there and besieging a detachment of government troops there.
The colonel said Iraqi troops entered Baiji, a city of about 200,000 people, from the south and west and took over the al-Tamim neighbourhood and city centre.
Islamic State had placed bombs along roads in Baiji and deployed snipers to keep government forces from advancing, tactics used in other cities held by the ultra-hardline Sunni group, which controls swathes of both Iraq and Syria.
"There are IEDs (improvised explosive devices) and snipers that are slowing down the advance, but the presence of the air force has facilitated the process of dismantling the IEDs in order to push forward," said the colonel.
"The areas taken so far are 6 km (4 miles) away from Baiji's refinery," he added. He said 12 militants had been killed. Baiji resident Sultan al-Janabi told Reuters by telephone from his house that clashes had been raging since the advance, the first time security forces reached the city centre since launching a new encirclement strategy at the end of last month.
"Violent confrontations are taking place in Baiji right now. I've been hearing continuous fire and loud bangs," said Janabi.
Baghdadi's fate unclear
US officials said on Sunday they had no information to indicate Islamic State commander Baghdadi had been wounded in air strike near the Iraqi city of Mosul, or if he was even in the convoy that was hit on Friday night.
The officials, speaking on condition of anonymity, were asked about an account on Twitter that said Baghdadi had been wounded.
One official said that "nothing has changed" since Saturday, when the US military said it was unclear if Baghdadi was present at the time of the strikes which targeted 10 vehicles.
A Twitter account claimed Baghdadi had been wounded but other accounts that support Islamic State said the report was untrue.
A member of western Anbar Province's security committee said he had heard unconfirmed reports that Baghdadi had been wounded and moved to Syria.
Iraqi officials and witnesses said there had been an air strike in Anbar, and Islamic State had cleared a hospital so that leaders of the group who had gathered for a meeting which was attacked could be treated for injuries.
Several other Anbar officials gave contradictory reports on Baghdadi's fate. State television cited reports that Baghdadi had been wounded. It gave no further details.
Even if Baghdadi were killed, Iraq would still face the challenge of defeating a group which quickly defeated its military in the north in June and is determined to expand a self-proclaimed caliphate.
The United States, which fought Islamic State's predecessor al Qaeda during the American occupation of Iraq, will send up to 1,500 more troops to train Iraqi forces. Britain also plans to send trainers.
US air strikes, launched after Islamic State beheaded Western hostages, have slowed down the Sunni insurgents and enabled Iraqi security forces to make some gains.
Police general killed
On Friday night, a suicide bomber rammed a truck packed with explosives into a Humvee transporting senior police commander General Faisal Malik, one of the supervisors of the campaign against Islamic State militants surrounding the refinery. The general and two policemen were killed.
The truck used in the attack was armoured, the army colonel and a provincial police command centre said, suggesting Islamic State had seized it from defeated Iraqi troops. Tanks and anti-aircraft weapons have also been taken.
The army colonel estimated that Iraqi forces had taken about 40 percent of the city centre. That could not be independently confirmed.
Iraqi security forces have used helicopters to attack Islamic State insurgents surrounding the refinery. But months of operations have failed to rescue comrades trapped inside and ensure the strategic site will not fall into the hands of Islamic State, who have used oil and fuel to fund their self-proclaimed caliphate.
Iraqi oil industry officials estimate Islamic State is making multi-million dollar profits from the illegal trade. Government forces, including counter-terrorism units, inside the compound have been surviving on airdrops as military forces outside tried to drive Islamic State militants away.
The Baiji refinery was producing around 175,000 barrels per day before it was closed, a senior Iraqi official said in June. Iraq's domestic daily consumption is estimated at 600,000-700,000 bpd.