The federal Workplace Ombudsman is investigating the University of Wollongong over allegations it pressured new staff to sign Australian Workplace Agreements.

The National Tertiary Education Union claims two applicants for lecturing positions at the university were illegally offered jobs on the condition they signed the Australian Workplace Agreements (AWAs).

But the university yesterday denied any wrongdoing, describing the union's claims as "unfounded" and "surprising".

"The university rejects any assertion that it has operated in an unlawful way with regard to the employment of new staff in the Graduate School of Medicine," the university said.

The university had been "using the practice of offering AWAs to newly recruited staff from outside the university to its Graduate School of Medicine for two years, in accordance with federal law and the university's enterprise agreements", the statement said.

The union has requested the university be prosecuted for failing to offer a choice between the AWA and a collective agreement negotiated in 2005.

"The people who contacted us were offered jobs, but only under an AWA," said the union's NSW legal officer Trish Mullins.

"This is illegal. If the university wants to offer an AWA, they have to also offer the enterprise agreement. There has to be a choice."

Ms Mullins said the defeat of the Howard government at the last election should have sent a message to employers that pressuring staff to sign AWAs was unacceptable.

"It's a very peculiar practice after the federal election, which made it clear that forcing people into AWAs was unpopular with the public.

"We hope they'll revisit their practice on this, but we'll pursue it as far as we can legally," she said.

A spokesman for the Workplace Ombudsman confirmed an investigation was underway into the union's allegations that the university breached the Workplace Relations Act, particularly "the collective agreement to provide a choice when offering an AWA."