Britain's Times Higher Education magazine asked more than 17,550 academics from across the world to rank the ''best'' universities, in terms of research and teaching reputations, for 2012.

In reputation terms, Australia's universities improved this year, with the University of Melbourne voted the 43rd best in the world, up from 45 last year.

The ANU leapt to 44 this year, up from the 51-60 grouping last year, the University of Sydney was voted 50, up from the 51-60 bracket and The University of Queensland was placed in the 71-80 bracket.

While the ANU's international reputation will be bolstered by the results, Vice-Chancellor Ian Young said they were more spin than substance.

''University rankings provide a very blunt and imprecise measure of the rich diversity of talent and excellent that exists on all university campuses,'' he said.

The University of Sydney's acting Vice-Chancellor Stephen Garton said the results were ''extremely encouraging'' and underlined the institution's growing international reputation.

''I congratulate the whole university community for their efforts in bringing about this recognition.''

Times Higher Education editor Phil Baty said the reputation index was ''very good news for Australia''.

''This is clear evidence that Australia's universities are rising in stature internationally, while competitors in US and UK are seeing their global brands suffer,'' he said.

But the findings also suggest Australia has a global image problem, with ANU and the University of Melbourne having a lower reputation than performance, according to the way the rankings are measured.

A separate Times Higher Education survey, the world rankings, measures more objective marks of success including teaching outcomes, research volume, journal citations and industry income.

In that survey the University of Melbourne and ANU rated better in performance (37 and 38 respectively) than their reputation performances of 39 and 40.

The University of Sydney was ranked 58 in outcomes globally, compared with its reputation rank of 50, and the University of Queensland 74, compared with its reputation rank of 71-80, indicating these institutions have healthy reputations.

The reputation ranking survey asked academics to name a small number of ''the best'' universities for research and teaching, in their specialist discipline, based as far as possible on direct experience.

''So we are looking only at subjective opinion - but it is expert opinion from those who know best about excellence in our universities,'' Mr Baty said.

''The academics who make the judgments for the rankings will be basing their answers on subject specific experience - they will be thinking of which department has been producing the most exciting research, who is attracting all the star professors, or which department they would recommend to their brightest graduates for the best postgraduate supervision.''

He added, ''I've argued in the past that Australia may have an image problem - with its performance on our global reputation-only index falling behind its performance based on the hard-objective indicators we use in the overall world university rankings.''