'Harry Potter' Series Racist Death Threats Get UK Police Attention

United Kingdom authorities are aware of death threats to a Black star of the upcoming HBO 'Harry Potter' series ... and they've been in contact with the production, TMZ has learned.

The Hertfordshire Constabulary -- which polices the area where the series is filming -- tells TMZ ... a police report has not been filed, but they are aware of threats targeting actor Paapa Essiedu. We're told officers are in contact with Warner Bros. UK Studio.

If you don't know ... HBO head honcho Casey Bloys recently told reporters the show, based on the beloved books by J.K. Rowling, upped security while filming after Essiedu got threats regarding his casting as Professor Severus Snape -- the character played by late legend Alan Rickman in the film series.

It's worth noting that the first trailer for the series dropped the other day ... and it's been inundated with repulsive racist comments about Essiedu playing Snape.