Coalition air strikes killed around 25 Islamic State fighters on Wednesday near the northern Iraqi city of Baiji, residents told Reuters.
They said a series of bombings beginning in the early hours hit the town of al-Siniya, west of Baiji, a strategic city adjacent to the country's largest refinery, part of a multinational effort to check the group's progress.
Iraqi army tanks and armored vehicles on Wednesday also fought off an advance by Islamic State militants on the town of Amiriya Fallujah, west of the Iraqi capital Baghdad, army sources said.
The sources added that around 400 fighters amassed in the nearby towns of Fallujah and Karma the day before, piling pressure on the capital's western flank.
Government forces fought back Islamic State outside Amiriya Fallujah - which faced a siege by the militants for much of this month and is the last government-controlled town before the key provincial city of Fallujah.
Soldiers destroyed five of the fighters' vehicles, a security source said.
There were no immediate reports on the number of casualties from the fighting there, but the militant advance appears to have been halted.
The United States and other Western countries have repeatedly bombed the Sunni jihadist group's positions in Iraq - including in the Fallujah area on Wednesday - and Gulf monarchies have also taken part in air strikes against it in Syria which began last month.
Declaring a caliphate, or Muslim theocracy, Islamic State took advantage of sectarian warfare and weak state control to grab swathes of Syria and Iraq earlier this year.
Islamic State fighters have also laid siege for a month to Kobani, hundreds of kilometers to the northwest on the Turkish-Syrian frontier, and only intense bombardments by US-led coalition warplanes have halted their advance.
