A university professor suspended for alleged "inappropriate sighing and making ironic comments" has been cleared of wrongdoing.

The University of Warwick's Thomas Docherty, professor of English and comparative literature, was suspended for nearly nine months after being accused of undermining the authority of the former head of the English department, Catherine Bates.

The case against the professor is said to have cited three incidents in which he is alleged to have undermined Professor Bates, including sighing, "projecting negative body language" and making "ironic" comments when interviewing candidates for a job in the department.

But Professor Docherty, said to be a prominent critic of the marketisation of higher education, has now been cleared of all accusations, according to the University and College Union.

He is reported to have been banned from the campus for more than eight months, from writing references for his students without permission and from being allowed to return their work or provide guidance on their PhDs.

He is also thought to have been barred from contacting students to cancel meetings after the suspension – which dates back to January – causing some to turn up for abortive appointments.

Professor Docherty told the Times Higher Education: "I'm looking forward to getting back to teaching, working with students and colleagues, and writing again, as normal."

The lifting of the suspension was welcomed by the University and College Union but UCU regional official Anne O'Sullivan was fiercely critical of the Midland university's procedures.

"It beggars belief that an academic can be suspended with no contact with students or colleagues for almost a year while charges are finalised. The one thing this protracted process should ensure is that the University of Warwick looks closely at its internal procedures.

"There is clearly the need for a better structure to deal with these kinds of issues and to ensure that academics have a speedier form of redress. Academic freedom is a key tenet of our universities and staff should not be worried for their careers if they wish to speak out about matters of concern."

Dennis Leech, president of the University and College Union branch at Warwick, said: "The fact that a member of the academic staff can be suspended for almost nine months and subject to such a protracted disciplinary process suggests that there is a need to review the governance of the university."

He said a review was needed "not only from the point of view of fairness to the individual concerned who (and whose family) has had to live with the stress of being under a threat of dismissal all that time, but also from the institution's own point of view as a university in which academic freedom is paramount".

He added: "I hope the university will look again at how it can strengthen its procedures to protect and defend academic freedom, which this case exemplifies to be threatened from obtrusive managerialism."

A university spokesman said a full statement agreed in conjunction with the other parties involved would be issued in coming days.