Police say three Iraqi workers have been killed in a roadside bomb explosion in the western city of Fallujah.

A local officer says the blast occurred Tuesday when a device exploded near a vehicle carrying construction workers in the Naimiya district. He says three others were wounded.

There was no immediate claim of responsibility for the attack.

Baghdad declared victory over the Islamic State group in late 2017 following a three-year war that ended with the liberation of Mosul, Iraq's second largest city.

The Iraqi army, however, continues to wage frequent operations against IS "sleeper cells", which officials say are still active in certain parts of the country.

The extremist group has claimed numerous operations in recent weeks.