UCEA needs to "stop spinning" and "fix its national degree scandal" said UCU.
The union was responding to UCEA's claims about the impact of the marking boycott.
UCU general secretary Jo Grady said: 'Over 5,000 students have already been told their degrees have been impacted, and we are still around a month away from most graduations. UCEA urgently needs to stop spinning and start trying to fix its national degree scandal before it gets even worse.
'UCEA's figures account for less than half of the universities impacted and don't include students in non-graduating years. They also don't acknowledge the absurd criteria institutions have created to bypass their normal academic standards - for example, the University of Nottingham's default position is for students to graduate with 'partial degrees'. Students aren't graduating, staff aren't being paid. Meanwhile, the employer body responsible for solving this mess is wasting its time issuing press releases. It is time for UCEA to stop the truth twisting and get back to the negotiating table with a better offer.'