NEW : A police officer is injured as a handful of far - left and far - right demonstrators clash . The left wing march was peaceful apart from the actions of a few `` hard core '' protesters who wanted to cause trouble , Husted said . Europe : Some 200 - 300 members of European far - right groups rally in London , police say . NEW : About 5,000 people turn out for a counter anti - fascist demonstration , police say . The far - right English Defence League says it wants to highlight the threat of Islamic extremism .
NEW : A police officer is injured as a handful of far - left and far - right demonstrators clash . Europe : Some 200 - 300 members of European far - right groups rally in London , police say . NEW : About 5,000 people turn out for a counter anti - fascist demonstration , police say . The far - right English Defence League says it wants to highlight the threat of Islamic extremism .