Neil Holmes, a UNISON steward who was employed as a research assistant, claimed he was unfairly made redundant by the college, in Lincolnshire, after he acted as a whistleblower to highlight fraud.
Mr Holmes, of St Andrew's Way, Immingham, told the hearing in Hull that he became concerned after hearing claims made by former employees that in the autumn of 1999, certificates were issued to learners that had been fraudulently produced.
Mr Holmes claimed that he told college principal Daniel Khan at a meeting last year. He said that in 2001 lecturer John Treacey had contacted him to say that his curriculum manager, Michael Braham, had asked him to amend records of teaching hours on some courses to increase the total and enable the college to claim funding in a higher fee band.
He said former teaching and learning observer David Robinson met him and Mr Khan on July 9 2001. "The allegation was connected with the fraudulent production of City amp; Guilds certificates concerning students of construction and engineering courses. I told Mr Khan that this activity was alleged to have taken place in autumn 1999 and that I had been informed that (former principal) Marylin Hawkins had been involved.
"This meant instructing at least one employee to physically create fraudulent certificates. I had been told that this was done by copying the certificates, deleting the names, re-copying them and then entering the new name and re-copying it.
"I then told Mr Khan that two lecturers delivering courses in health and safety had been instructed on 28 June 2001 by their curriculum manager, Michael Braham, to back-date amendments to the register to enable the college to claim fees at a higher fee band."
Grimsby College corporation claims Mr Holmes was not a whistleblower as the allegations into the fraud were not raised by him but by workers he represented through UNISON.
The hearing continues.