Police say a man in his 30s, who is believed to be Sudanese, is in custody.
Disorder broke out in Southampton close to where the 18-year-old student was murdered.
The Conservative leader says the rules have led to public bodies becoming "institutionally incompetent".
Stefania Glowka pleaded guilty to the manslaughter of her mother based on diminished responsibility.
Glasgow City Council leader Susan Aitken says the planning and consultation process regarding the land is likely to last until about 2030.