Health watchdog Monitor put Colchester Hospital into "special measures" yesterday following claims that staff were bullied into changing records of cancer treatment waiting times.

Unison welcomed the decision on the Chelmsford Hospital University foundation trust, which is being investigated by police.

Inspectors from the Care Quality Commission (CQC) found "inaccuracies" with waiting time data at the hospital, with some suffering "undue delays."

Staff told inspectors that they had been "pressured or bullied" into changing the data so it appeared people were being treated according to national guidelines.

As a result some patients may not have had the treatment they needed in time, said the CQC.

Under special measures the trust will be required to "put right the patient quality, safety and governance concerns" flagged up by the CQC.

An improvement director will be appointed "to ensure the trust turns itself around" and the hospital will be given support by a high-performing trust.

Chelmsford chief executive Dr Gordon Coutts said the trust was contacting 30 patients - or next of kin where patients have died - identified by the CQC report.

Unison regional head of health Tracey Lambert said Monitor had made the right decision.

"The trust board has lost the confidence of patients and the public in north-east Essex and people want to see strong, positive action to improve healthcare at the hospital.

"Unison members alerted executive directors at the hospital that they were being bullied into falsifying data relating to the treatment of cancer patients but their concerns were not dealt with.

"We know that our members in other departments also believed they would not be listened to if they spoke out about their fears. Unison repeatedly made this point to the trust."

She called for "a significant change of leadership" at Colchester hospital in light of what has happened.