Det Supt Charles Moffatt, (pictured) the outgoing head of Northamptonshire Police's professional standards department, said it was becoming increasingly common for members of the criminal underworld to try to infiltrate police forces up and down the country.

He said: "Organised criminals will try to place people into police forces in any role they can. They will be in a position to obtain highly-sensitive information and that information is incredibly valuable to the gangs.

"It is one of the many things that police forces across the country have to be aware of.

"Police officers dislike corrupt police officers even more than they dislike criminals, it is all about the breach of trust that is involved."

Det Supt Moffatt, who retires from the county force next week after 30 years fighting crime in Northamptonshire, has overseen the growth of the professional standards department and has played a pivotal role in ensuring a sustained reduction in the number of police complaints, culminating in Northamptonshire seeing the largest reduction of any force in the country in 2007/08.

He has led investigations into allegations of police corruption, including one involving the Metropolitan Police in 2008, and was instrumental in leading the change in the way police information was handled in the wake of the national Bichard inquiry.

One of Det Supt Moffatt's last major roles before he retires has been to oversee Operation Landslide, one of the biggest ever operations to tackle drug dealing, money laundering and organised crime in Northamptonshire.

Tens of thousands of pounds of drugs, stolen cars and counterfeit currency have so far been recovered by officers working on the operation.

Several suspects have been remanded in custody for a range of alleged offences including supplying class A drugs, handling stolen goods and conspiracy to supply drugs.

The climax of the top secret investigation came in March when more than 200 officers from three forces made dawn raids on homes across Northamptonshire with subsequent raids in the days and weeks that followed.

The case saw a total of 26 people arrested as part of the overall investigation, including a semi-professional rugby player and two serving police officers.

The Chronicle & Echo reported earlier this week that the two officers had been released without charge but Det Supt Moffatt confirmed one of them, a male officer working for Northamptonshire Police, would now be subject to an in-depth internal investigation and could face disciplinary proceedings.