Washington, May 18 (IANS): US Secretary of State John Kerry on Monday said he was confident about the fight against the Islamic State (IS) terrorist group despite setbacks like the loss of the city of Ramadi in Iraq.

Kerry, who is traveling through Korea, said the fight against the terrorist group would be a long one, and that it would be tough in the Anbar province of western Iraq where Iraqi security forces are not built up, NBC News reported.

He said that Ramadi was a "target of opportunity" but he was confident that in coming days, the loss could be reversed.

Ramadi fell to the Islamic State group on Sunday, as Iraqi forces abandoned their weapons and armoured vehicles to flee the provincial capital in a major loss despite intensified US-led airstrikes.

The IS has reportedly executed some 500 people in Anbar province amid mounting calls to send reinforcements to the province.

On Sunday, Anbar Provincial Council announced that the Sunni radical group has executed more than 500 civilians during the latest terrorist incidents in Ramadi.

Deputy President of Anbar Provincial Council Faleh al-Essawy said in an interview with al-Sumaria TV channel, "The IS militants had carried out executions of more than 500 civilians, most of whom were women and children, in one area in Ramadi city."

He pointed out that "unarmed civilians are the most affected people during those latest security incidents".