Iraqi forces, backed by US-led airstrikes, entered a strategic Islamic State-controlled area in the country's west on Saturday, hours after starting a major offensive there against the extremist militia, military sources said.
The Iraqi forces stormed the frontlines of Khalidiya Island, around 23 kilometres east of Ramadi, the capital city of the western Anbar province, after encountering weak resistance from Islamic State militants, the sources added.
"The international [US-led] coalition warplanes have bombed heavily the positions of the radical organization in the area," a military official told dpa on condition of anonymity.
"At least 20 militants have been killed in the air raids," the official added.
The government forces' advance into the area was slowed by fears of mines and other explosives that might have been planted by Islamic State, according to the official.
No figures were given for casualties among government troops.
Earlier Saturday, government forces backed by the powerful Shiite Popular Mobilization militia launched a major operation to "liberate" Khalidiya, an Iraqi military media centre said.
Khalidiya is strategically important because it is located on supply routes for Islamic State militants, who have lost ground in Iraq in recent months.
In December 2015, Iraq regained Ramadi from Islamic State as part of a sustained US-backed campaign against the radical Sunni group.
The militants have since used Khalidiya as a launch pad for mounting attacks on Ramadi.
Last month, Iraq announced retaking full control of the western city of Fallujah from Islamic State.
The al-Qaeda splinter group still controls Mosul, Iraq's second largest city.