A U.S.-backed rebel alliance says it has begun a battle to capture the Syrian city of Raqqa, the extremist group Islamic State’s (IS) stronghold and self-declared capital in the country.
"We declare today the start of the great battle to liberate the city of Raqqa," a spokesman for the Syrian Democratic Forces (SDF), Talal Silo, told journalists on June 6.
The Britain-based Syrian Observatory for Human Rights said the SDF, a coalition of Syrian Kurds and Arabs, has been engaged since dawn in heavy fighting with militants on the eastern and northern outskirts of Raqqa.
The U.S.-led coalition fighting IS in Syria and Iraq said the fight for Raqqa would be "long and difficult" but would deliver a "decisive blow" to the militants.
Officials of the coalition estimate that there are 3,000 to 4,000 IS fighters remaining in the city preparing for the assault.
The offensive on Raqqa comes at a time when U.S.-backed Iraqi government forces say they are close to fully liberating Mosul, the final significant IS stronghold in Iraq.
IS militants seized large swaths of Syria and Iraq in an offensive in June 2014.