According to the latest estimates, there are about 100,000 people in the UK are living with HIV, although experts say a quarter of those who are infected do not know they have it.
In 2011, there were around 6,000 new diagnoses of HIV in the UK.
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The violence began after a counter-protester allegedly doused a female rally organiser with pepper spray.
As temperatures climb through the day, the warmest spots are likely to be across western parts of Northern Ireland and western Scotland.
The foreign secretary has criticised internet and social media giants for failing to detect and remove extremist material posted online.