If you think this might be urgent or time critical, please call the Anti-Terrorist Hotline on 0800 789 321.
Find out below the different ways you can tell us about possible terrorist activity either in the UK, or that might affect the UK. Any piece of information could be important; no matter how small or insignificant it may seem, it's better to be safe and report it. You can help us prevent terrorism and save lives.
Even if you’re not sure, please let us know so that we can investigate. Action will only be taken after the appropriate checks have been carried out.