Syria war: What has happened in Afrin?

Syrian rebels backed by Turkey have taken control of the centre of the city of Afrin.

Afrin lies near Turkey's border with Syria, and Turkish forces have fought for two months to clear it of Kurdish YPG fighters.

Turkey regards the YPG as terrorists, insisting they are linked to Kurdish rebels in south-eastern Turkey. However, the US sees them an crucial to the fight against the Islamic State group.

The BBC's Turkey correspondent Mark Lowen explains what happened.