The National Institutes of Health has put a $9.3 million grant to Emory University on hold while it investigates the suspect dealings of Professor Charles Nemeroff.

Earlier this month the US psychiatrist stepped down as chairman of Emory University’s department of psychiatry and behavioural sciences after his relationship with pharmaceutical companies was called into question.

Senator Charles Grassley, a Republican member of the US Senate Finance Committee, claimed this month that Nemeroff was paid speaking fees by GlaxoSmithKline but “failed to report approximately half a million dollars” earned from “dozens of talks given to promote drugs sold by the company”.

The payments were made during a five-year period in which Nemeroff was serving as the principal investigator in a government-funded collaborative antidepressant research programme between the university, GSK and the National Institute of Mental Health.

According to reports, the university had instructed Nemeroff to decline payments of more than $10,000 annually during the grant.

A report by the New York Times earlier this month stated the professor had received more than $2.8 million between 2000 and 2007 from consulting activities with drugmakers and of that he failed to report at least $1.2 million to Emory University.

The NIH is now investigating whether Nemeroff disclosed payments properly and has requested the professor cease involvement in any agency-funded projects. The university has confirmed Nemeroff has stepped aside from three such projects.

In August, the university was notified the NIH was suspending the grant.

In a statement, Nemeroff said he was co-operating with the investigation.

“To the best of my knowledge, I have followed the appropriate University regulations concerning financial disclosures. I have dedicated my career to translating research findings into improvements in clinical practice in patients with severe mental illness. I will cooperate fully and work with Emory to respond to the alleged conflicts of interest issues raised by Senator Grassley and his staff.”

Emory officials are currently conducting an internal review of the allegations and have promised a fair, thorough, and even-handed investigation of the claims.