The Colchester Hospital University NHS Foundation Trust, the Care Quality Commission (CQC) has been reported to the police after staff complained that they were being "pressured or bullied" to falsify data relating to cancer patients.
22 cancer patients suffered "undue delays", and in some cases, people did not get their treatment within the required 62 days.
In three cases, delays exceeded 100 days.
CQC inspectors found that there were "inaccuracies" with waiting time data relating to cancer treatment.
ITV News reporter Ben Chapman reports:
Staff told inspectors they were "pressured or bullied" to change data relating to patients and their treatment to make it seem like people were being treated in line with national guidelines, a CQC spokesman said.
As a result some patients may not have had the treatment they needed in time, the spokesman added.
The watchdog has passed its findings to Essex Police.