Secretary of their association N.G.A. Karunatilake has written to higher education minister Lakshman Kiriella, alleging it was a political appointment.
The lecturers demand the cancellation of the appointment before December 20, and warn of union action if the demand is not met.
Copies of the letter have been sent to the president, prime minister and the UGC.
When contacted, Tennakoon said he was unaware of such a letter being sent against him, and declined to comment.