Concerns have been raised about the growing number of websites offering students bespoke academic essays in return for a fee.
Half of Welsh universities have seen an increase in the number of plagiarism cases being investigated in the past five years, figures have shown.
The Quality Assurance Agency, which monitors standards in higher education, said it was discussing the issue with universities.
It added the sites were not illegal.
Figures obtained by BBC Wales Today showed the number of undergraduate students investigated for potential plagiarism in their coursework at Cardiff, Swansea, Aberystwyth and Cardiff Metropolitan universities more than doubled between 2010-11 and 2014-15.
A gradual increase was also seen in the number of postgraduate cases at Swansea, Bangor and Aberystwyth.
Other universities have seen the number of plagiarism cases vary during the same five-year period.
It is believed that improvements in technology, greater student numbers and increasing university costs - which places extra pressure on students to succeed - have all contributed to the increase.
Mary Paget, director of academic integrity at Swansea University, said: "Where we are talking about what you would call low-level plagiarism, we are always going to have naïve students with various personal issues and we are always going to have to deal with those.
"I think what is more of a concern is the sheer number of bespoke essay writing sites - that is something which is causing a lot of universities concern."
It is believed there are about 1,000 websites - or essay mills - which offer students a bespoke academic essay in return for a fee.
One such website claimed that "papers will only be written by the most experienced and skilled writers who have excellent linguistic skills and impeccable grammar".
And that "being a person of the same professional field, they write your paper just as you like it".
The Quality Assurance Agency said: "Cheating and plagiarism has no place in UK higher education, and universities and colleges take their responsibilities in this area very seriously.
"These companies offer students essays in return for payment. They are not illegal, and they generally issue disclaimers warning against plagiarism.
"However, no matter how good policies and software are, it is difficult to detect whether tailored work has been written for a student by a third party such as an essay mill. We are now in the process of discussing this issue with partners in the higher education sector."
There is also concern about how, in some cases, essay mills are targeting students on social media, as well as the financial implications for students who choose to use this type of service.
Robiu Salisu, education officer at Swansea University's Students' Union, said: "They will give you a taster of the work and then they will say if you want the full thing you have to pay more and more money. It's not worth it.
"It's not just to do with the repayment of the money for the commissioning either, because once you are found out you will faced with academic misconduct and that will jeopardise your future in higher education."
It is understood that a paper was recently put before Swansea University's learning and teaching committee to ban these websites on campus.
Other Welsh universities said they treat any form of academic misconduct very seriously and that they advise students on their academic regulations and continue to work to improve this process.