Detectives in The Hague have lost key evidence relating to their online infiltration of a suspected jihadi network, the NRC said on Thursday.

The paper says that investigators set up a fake Facebook profile in an effort to break into jihadi circuits in The Hague. The account, in the name of Aboe Noewas, was used between 2013 and 2014.

The investigator sent friend requests to suspects in an effort to win them over, the NRC says. However, the police officer ‘forgot’ to save his own comments and the information has vanished because the account has been removed.

Defence lawyers say the lost evidence is of crucial importance to the case because the police are now unable to prove they are not guilty of entrapment. For example, one photograph which the fake account shared on Facebook was spread by the suspects and now appears in the evidence file.

Although the public prosecution department will not confirm that crucial information has been lost, sources have told the NRC this is the case.

The evidence gathered by the undercover operation forms part of the case against nine men and one woman currently taking place at Amsterdam’s high security court.

On Wednesday, the NRC reported that a key witness for the prosecution now claims he made up his statement incriminating some of the suspects.