A memorandum of understanding (MOU) to ensure consistent and thorough handling of cases involving undercover officers where there may be a criminal prosecution has been signed by the CPS, ACPO, SOCA and HMRC.

The agreement, signed in June 2012, directs that close and early working between relevant organisations takes place so that the best evidence is gathered for prospective court cases, and more criminals are brought to justice.

The Director of Public Prosecutions, Keir Starmer QC said: "Evidence from undercover policing is a powerful tool in prosecution cases, but it is one that must be wielded with great care and responsibility.

"This agreement ensures that investigators and prosecutors work closely together from the very outset of any relevant covert operations and that all necessary actions are carried out and documented, so that this very complex area of law is consistently and thoroughly adhered to by all those involved."

ACPO undercover working group chair Deputy Assistant Commissioner Patricia Gallan said: "Undercover officers play a critical role gathering evidence and intelligence to protect communities from harm. It is one of the most challenging areas of operational activity undertaken by the police service and as such ensuring close and early working with relevant organisations is key to ensuring best evidence and justice outcomes."

The MoU applies whenever:

1. There is a use and conduct authorisation for the deployment of an undercover officer under Part II of the Regulation of Investigatory Powers Act 2000 (RIPA).

2. The undercover officer has been authorised in circumstances in which a prosecution is contemplated, or where it has become apparent that there is the clear potential for a prosecution.

3. The investigation is being carried out (alone or jointly) by any ACPO police force, the Serious Organised Crime Agency, the UK Border Agency or Her Majesty's Revenue and Customs; and

4. Any prosecution or advice on a possible prosecution would fall to be considered by the Crown Prosecution Service.

This MoU will be reviewed after it has been in place for 6 months, so that its implementation and impact can be assessed.