UTAS chancellor Michael Field said there was nothing untoward about the spending and that travel was necessary to maintain the university's "world standing".

"The university is undergoing a transformative change process in campuses and curriculum, and has been looking and talking with universities which are leading in this field, especially in the US," Mr Field said.

He said the vice-chancellor had led UTAS through a period of "unprecedented growth, international student numbers and a capital expenditure program which has kept the Tasmanian building sector busy during relatively quiet economic times".

Leaked travel documents, obtained by the ABC, showed Professor Peter Rathjen - who receives an annual wage of at least $855,000 - travelled to North Carolina, New York and Paris, with his wife, taking economy, business and-first class fares in September and early October 2015.

The couple spent three nights at the Sofitel Hotel in New York, costing UTAS more than $1100 a night, with the total trip costing more than $37,000.

Professor Rathjen also spent Christmas and New Year in Mexico, costing the university $15,000.

The university's travel policy stated business travel should be by economy class except where authorised by the chief operating officer, or if the staff member's employment contract authorised a higher class of travel.

National Tertiary Education Union Tasmanian division secretary Kelvin Michael said the revelation was disappointing, considering increased workload pressures on staff at UTAS.

"Since 2009, academic staffing levels have decreased while the numbers of students attending the university has increased by 25 per cent," he said.

The National Union of Students called for greater "transparency" within the university.