Metropolitan Police Service
Government under fire as it says industry "must take responsibility".
Three men have been arrested.
It is worrying to see forces so cowed in dealing with a small group of protesters that has shown a predilection for violence and intimidation.
Sean Rigg died in 2008 after he was held in Brixton Police station.
Neil Basu added that a no-deal EU exit would be "very bad" for policing.
Officers had been responding to a call about a man threatening members of the public.
Ahmed Munajed is due to appear at Westminster Magistrates' Court on Wednesday.
Abdulah Husseini was due to appear on December 18.
Police are appealing for information.
The MP said she feared people would start leaving their jobs if the abuse continues.