Iraqi military forces reached the centre of the northern city of Baiji on Sunday to try to break an Islamic State siege of the country's biggest refinery nearby, according to an army colonel and a witness.
The troops entered from the south and west and took over the al-Tamim neighbourhood and city centre, said the colonel.
Baiji resident Sultan al-Janabi told Reuters by telephone from his house that clashes have been raging since the advance, the first time security forces attained the city centre since launching a new encirclement strategy at the end of last month.
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 the ultra-hardline Sunni militants who have used oil and refined products to fund their self-proclaimed caliphate overlapping the borders of Iraq and Syria.
Late last month, Iraqi government forces tried a new approach, circling Baiji from the west in order to retake the city and cut off supply lines to insurgents surrounding the refinery a few km (miles) away.