The College of Technology London, which formerly taught the majority of Trinity Saint David's international students, said last month that it was pulling out of the arrangement because of "poor quality assurance and administrative standards" over an 18-month period.
Trinity Saint David has strongly denied the claims, saying the allegations of low standards were "inaccurate", "misleading" and "entirely spurious".
It said it had been seeking an "orderly exit strategy" from the link-up before December because of concerns over quality at the College of Technology London.
In a statement on its website, the private college alleges that in 2010 "45 per cent of documentation sent by TSD [was] incorrect" and "in 2011, 25 per cent of TSD academic correspondence to students [was] incorrect".
Trinity Saint David said these claims were "completely disingenuous" and the reason for the inaccuracies was that the college failed to integrate its student records system with that of the university.
The college has also claimed that the results data sent to its students were "consistently wrong" and "many students that should have passed have failed, and students that have failed modules passed".
In response, the university said that it was "obviously the case that during the re-marking and moderation processes, marks and the resultant outcome can be subject to change".
It also blamed the college for not passing on certain information about candidates, citing this as a reason why "extensive checking" of results was required.
The relationship between Trinity Saint David and the college followed a "franchise" model, where students undertook courses identical to those at the university and both institutions marked results.
The partnership began in 2005 with the University of Wales, Lampeter, which merged with Trinity University College in 2010 to form Trinity Saint David.
By August this year, Trinity Saint David will have merged with the University of Wales and Swansea Metropolitan University.
The College of Technology London is currently searching for new partner universities.