Mr Willis says the reputation of UK universities is at stake
The threat to quality is the most serious issue facing higher education, says Phil Willis, chair of the Commons' universities committee.
Mr Willis' committee is to question the chief of the university standards watchdog on Thursday.
He says universities must put their house in order, after reports of degree grades being inflated or wrongly given.
Mr Willis says he wants to hear from the watchdog how it is tackling abuses of degree standards.
The House of Commons select committee on innovation, universities, science and skills is to take evidence from Peter Williams, chief executive of the Quality Assurance Agency (QAA).
The UK has the "most prestigious higher education system in the world," says Mr Willis, which earns the country billions of pounds each year.
"Therefore to put that under threat, which is what will happen if people do not believe in its quality, is the most serious issue affecting higher education," says Mr Willis.
He told the BBC News website he had received more e-mails on this matter than anything previously tackled by his committee, and that there was a pressing need to examine how the integrity of degrees could be protected.
"There are serious heads of department who are concerned that the quality of the degrees they are awarding do not match the quality of the students," says Mr Willis.
Among the issues brought to his attention, he says, have been concerns about undergraduate degrees awarded regardless of students' ability, the credibility of postgraduate degrees and the over-recruitment of overseas students in a way that damages the running of courses.
Mr Willis warns university watchdogs and higher education leaders they cannot close ranks and ignore such concerns.
"I'm afraid that isn't good enough. I expect them to be able to demonstrate that abuses are being weeded out."
He says he expects to hear from Mr Williams how he is tackling "everything from fraud to plagiarism to the abuse of the higher education system".
"I'm looking for Williams to come along and say 'we have found problems and this is what we've done about it. These students have been downgraded, kicked out or whatever'."
"If he says that nothing is happening at all, that it's all figment of the imagination - then the advice to my committee will be to look further."
Lack of transparency
Mr Willis says there needs to be much greater transparency in this traditionally self-regulating sector, particularly when it is expanding.
Fee-paying students, taxpayers and employers who recruit graduates have a right to be able to rely upon the credibility of the degree system.
He says that the committee of MPs will expect the head of the QAA to be able to show that his watchdog, which is funded by subscriptions from universities, is a genuinely independent and effective body.
Mr Willis says he does not want an "Ofsted for higher education" but he does support the need for an external body to provide evidence of the rigour of university standards.
This greater accountability should be a condition of the extra funding which will accompany the expansion of higher education, he says.
"If universities are going to retain their reputations, they have got to be more transparent."
Universities should have confidential, open-access systems in which academics and students can raise concerns, he says.
A feature of academics' complaints has been their fear of speaking publicly, because of the threat to their careers.
With plans for many more students to enter the system, he says it remains a problem that there are so few "hard facts" about university standards and an absence of "the simple statistics you'd expect about performance".
For instance, there are no official figures for failure rates for postgraduate courses.
A series of whistleblower stories and large numbers of responses from academics have highlighted deep concerns within universities about the way that degrees are assessed and awarded.
This has included claims about overseas students who can barely speak English being awarded postgraduate degrees, questions about the credibility of the external examiner system and the inflation of grades to improve the image of institutions.
"It is up to universities to put their house in order. This is a multi-billion pound business and you cannot afford for short-term gain to have the reputation tarnished. It has to retain its currency in an international market."