Universities in Birmingham, Coventry, Warwick and Wolverhampton have been accused of secrecy after refusing to answer questions on spending on flights, hotels and expense claims.
The group was among 24 universities out of 155 who failed to respond to a Freedom of Information request from the University and College Union (UCU).
A report, based on data from the FoI request, showed university bosses were spending as much as £60,000 a year on air fares and enjoying first class and business class flights.