Your web browser is out of date. Update your browser for more security, speed and the best experience on this site.
Skip to Main Content ⏎.
  • To report an imminent threat call 999 or ring the Anti-Terrorist Hotline on 0800 789 321
  • Current national threat level: SUBSTANTIAL
  • Find out more
Contact Us

Contact Us

Immediate threats to life or property

If your information relates to an imminent threat to life or property, please contact the police on 999 or the Anti-Terrorist Hotline on 0800 789 321.


We are not a law enforcement agency and we do not investigate matters that do not involve threats to national security. If you have information about criminal activity that is not related to national security, contact your local police force.
Please note: If you receive a call from MI5, it will not come from any of the numbers listed below. Please treat any calls received from these numbers with caution, and do not divulge any personal information or banking details.

Stone spiral
Huge pendulum

Suspected threats to national security

If you know something about a threat to national security such as terrorism or espionage, we want to hear from you.

We will treat your information and any personal details in confidence unless you tell us otherwise or exceptionally if there is a need to share it with appropriate parties such as the police.

You can send us information through our online contact form. You can remain anonymous if you wish. Your message will be sent securely. You will see an acknowledgement when you have sent your message.

All messages will be read. However, we cannot promise to respond to all of them.

Alternatively, you can contact us by telephone via:

  • Freephone 0800 111 4645 
  • 020 7930 9000 (standard call rates apply)
  • +44 20 7930 9000 (international callers only)

Please do not use the phone line for making enquiries about general matters or recruitment issues. We will never use these numbers to call you back, so treat any call that seems to come from these numbers with caution.   

Or you can write to the following address:

The Enquiries Desk
PO Box 3255
London SW1P 1AE

Please be aware that written correspondence posted in the UK may take up to a week to reach us.

All calls and correspondence will be treated in confidence (see our privacy policy).

Recruitment issues

If you have a query about applying for a job with MI5 we suggest that you look first at our careers section, which may answer your questions.

If you still need to contact us about a recruitment issue, or you are having problems applying for a job with MI5 or accessing your online application, please contact the Recruitment Office by email or telephone:

Please do not use the general enquiry web form to submit queries about the recruitment process or your application to our website team. The Recruitment Office is best placed to help you.

Please note that due to the volume of enquiries we receive, we are not able to accept invites to attend careers events or to develop educational materials submitted via the website.

Media enquiries

MI5 does not have a press office.

If you work in the media and you would like to ask about intelligence matters or MI5, please contact the Home Office Press Office.

General enquiries and feedback

If you wish to give us feedback or make a general enquiry that has not been answered by the information on this site, you can get in touch using the contact form.

All messages will be read, though we cannot promise to respond to all of them. There are also restrictions on what information we can provide, so if we do respond we may not be able to provide you with the information you request.

Cinquefoil Trust

The Cinquefoil Trust is a registered charity established to support current and former members of MI5, and their dependents and those in a family relationship with them, who find themselves in challenging circumstances. If you are in need of support and think you may be eligible for the Trust’s help, please contact us at the address below. If you wish to apply for support, or just to see whether we may be able to help you, please get in touch at Cinquefoil Trust, PO Box 3255, London SW1P 1AE. 

Complaints about our activities

If you wish to make a complaint about MI5, the Investigatory Powers Tribunal (IPT) will be able to help you.

Fact or Fiction

You can ask whether your relative used to work at MI5