BAGHDAD/BEIRUT (Reuters) - The U.S.-led coalition fighting Islamic State in Syria and Iraq said on Wednesday it was tightening the noose around militants in the Syrian city of Manbij near the Turkish border but expected them to fight to the end to defend their stronghold.
A U.S.-backed alliance of Kurdish and Arab fighters supported by coalition air strikes cut off the group's supply lines to Manbij in a rapid advance this month against Islamic State in the area.
The offensive aims to sever the group's only major route to the outside world.
But it has stopped short of an assault on the city itself out of concern for civilians inside, the U.S.-backed alliance says.
An IS counter-attack on Monday inflicted heavy casualties, monitors reported.
"We're around the city and we're coming in, and we've cut the lines of communication into it and the noose is getting tighter around the city," Baghdad-based U.S. Army Colonel Chris Garver told reporters.
"We are anticipating that that's going to be another good fight when we get in there."
"We've anticipated that they (IS) would hold Manbij till the last, that it would be one of those places that they defended till the end and we have not seen anything that's going to change that assessment right now," Garver said.
The Syria Democratic Forces, which include the Kurdish YPG militia and Arab fighting groups, has led the offensive on the ground.
A statement from the alliance on Tuesday said they had thwarted an IS counter-attack outside Manbij which included the use of vehicles laden with explosives.
British-based monitoring group the Syrian Observatory for Human Rights says scores of IS fighters and dozens of SDF fighters have been killed in the three-week offensive.
The U.S.-led coalition says at least 20 fighters from the Arab contingent of the SDF have died.
The Observatory said more than 3,000 civilians have fled Manbij during the fighting, and that clashes continue in the countryside around the city.
(Reporting by Stephen Kalin and John Davison; Editing by Richard Balmforth)