Alternatively, you can call the police confidentially on 0800 789 321.
All reports are kept confidential and you can report anonymously.
In an emergency always call 999.
What should I report?
Like other criminals, terrorists need to plan. You can report suspicious activity or behaviour - anything that seems out of place, unusual or just doesn't seem to fit in with everyday life.
Some examples of suspicious activity or behaviour could potentially include:
Do you know someone who looks at extremist material, including on the so-called Dark Web, or shares and creates content that promotes or glorifies terrorism?
Have you noticed someone embracing or actively promoting hateful ideas or an extremist ideology?
Meetings, training and planning can take place anywhere. Do you know someone who travels but is vague about where they're going?
Do you know someone with passports or other documents in different names for no obvious reason?
Suspicious materials can be ordered online as well as in store. Have you noticed someone receiving deliveries for unusual items bought online?
If you work in commercial vehicle hire or sales, has a sale or rental seemed unusual?
Have you noticed someone buying large or unusual quantities of chemicals, fertilisers or gas cylinders for no obvious reason?
Have you noticed someone acquiring illegal firearms or other weapons or showing an interest in obtaining them?
Terrorists need to store equipment while preparing for an attack. Have you noticed anyone storing large amounts of chemicals, fertilisers or gas cylinders?
Have you noticed anyone storing illegal firearms or objects that could potentially be weapons?
Observation and surveillance help terrorist plan attacks. Have you witnessed anyone taking pictures or notes of security arrangements or CCTV?
Cheque and credit card fraud are ways of generating cash. Have you noticed any suspicious or unusual bank transactions?
What if the information I give is wrong?
That's okay. If you have a genuine concern about something you've seen or heard, the police would much rather you told them than keep it to yourself. That way, specially trained officers can look into it. If it turns out to be nothing, that's good news.
If you would like more information or resources, visit www.gov.uk/ACT or follow Counter Terrorism Policing on social media: