BAGHDAD - Iraqi security forces launched a new offensive against Islamic State insurgents in the Sunni Muslim heartland of Anbar on Wednesday, seeking to build on a victory over the jihadist group last week in the city of Tikrit.
Fighting began in the western province's desert terrain as Prime Minister Haidar al-Abadi was touring Anbar, visiting Iraqi army units and pro-government Sunnis, his office said.
Abadi was expected to address the nation from Anbar later in the day.
Army officers said Islamic State militants were driven back on Wednesday in the Sijariya area east of the Anbar capital Ramadi and Falluja - the region's two key cities, where the ultra-radical Sunni group has been dominant.
Islamic State was retreating from Sijariya, trading mortar fire with government forces, military sources said.
A senior Iraqi officer in Ramadi said the purpose of clearing Sijariya was to secure supply routes to the nearby Habbaniya air base and to weaken the jihadists' grip on territory connecting Ramadi and Falluja.
Large parts of Anbar had slipped from the government's grasp even before Islamic State overran the northern city of Mosul last June and surged through Sunni areas of Iraq.
Security forces and Shi'ite Muslim paramilitaries have since regained some ground, although core Sunni territories remain under Islamic State control.
Shi'ite militia have played a leading role in reversing the insurgents' advances, but officials from predominantly Sunni Anbar have expressed reservations about a role for Shi'ite paramilitary forces on the battlefield.
Iraqi officials have argued for some time that Anbar should be the next major battleground, or that operations should be carried out there in parallel with the northern province of Nineveh, of which Mosul is capital, in order to isolate Islamic State in its strategic bastions along the Syrian border.
"In Anbar there are spots under government control and the troops are fighting IS," Deputy National Security Adviser Safaa al-Sheikh told Reuters in late March.
"You have these spots and can expand from them. We don't have this situation in Mosul."
Iraqi and US officials have come to see the value in striking Anbar now after months of debate over whether to try first to take Mosul, where Islamic State declared its Islamic"caliphate" and unfurled its campaign across Iraq last summer.
"Watching Tikrit has reminded people how difficult urban warfare is," said a senior Western diplomat on condition of anonymity.
The goal, the diplomat said, was to cut off IS supply routes from Syria to make it harder for it to reinforce Mosul.