Iraqi government forces said they seized back control of a major airbase on Saturday, a staging post on their way to the Islamic State stronghold of Mosul.
Special forces and regular troops, under air cover from the U.S.-led coalition, entered Qayyara airbase from the south and found fighters from the militant group appeared to have fled, said a senior army officer from the frontline.
"It's a strategic advance ... It will help speed up the offensive on Mosul," he added. The army has long said it wants to use the airbase as a launchpad for the recapture of Mosul about 60 km (40 miles) further north.
There was no immediate comment from Islamic State.
Iraqi Prime Minister Haider al-Abadi hailed the advance on his website, saying it would "be important for the liberation of Mosul".
Two years since Islamic State seized wide swathes of northern and western Iraq in a lightning offensive, the tide has begun to turn as an array of forces lined up against the militants have made inroads into their proclaimed "caliphate".
Abadi has pledged to retake Mosul - the largest city under control of the ultra-hardline Sunni Muslim militant group in both Syria and Iraq - by the end of the year.
The military's recapture of Falluja, an hour's drive west of the capital Baghdad, last month lent fresh momentum to the campaign to recover Mosul, the largest city in northern Iraqi with a pre-war population of about 2 million.
The insurgents stepped up a campaign of bombings on Shi'ite Muslim targets since the battle of Falluja, reigniting fears of an escalation of the sectarian strife.
The Shi'ites form a majority in Iraq but Sunnis are predominant in northern and western provinces where Islamic State proclaimed its "caliphate".