Mosques up security, British police boost presence after night of rioting in Sunderland

British police are putting more officers on the streets amid warnings of more violent disorder this weekend and mosques have tightened security after anti-immigration protesters torched cars following the murder of three young girls.

Riots involving hundreds of people — or thousands in one protest in London — have erupted this week, after false information spread rapidly online that the suspect in the killings in the northwest town of Southport was a radical Muslim migrant.

Police have said the suspect...