US colleges dominated a 2011 ranking of world universities issued by Shanghai's Jiaotong University on Sunday, with Harvard topping the influential list for a ninth year.
American institutions took 17 of the top 20 places on a list issued since 2003 and heavily focused on scientific research, but subject to criticism in Europe where officials say the criteria are biased against European schools.
Stanford University retook the second-place slot from the University of California, Berkeley, which fell to fourth place behind the Massachusetts Institute of Technology (MIT).
Three British universities made the top 20, with Cambridge in fifth place, Oxford in 10th and University College London at 20th.
The rankings are focused almost entirely on a university's achievements in scientific research, and do not cover the humanities -- prompting concerns that they do not accurately reflect an institution's overall performance.
Jiaotong uses criteria such as the number of Nobel prizes and Fields medals won by staff and alumni, the number of highly cited researchers on staff, and the number of articles by faculty published in Nature and Science magazines.
The list was the first global ranking of universities when it made its debut in 2003. It was intended to benchmark the performance of Chinese universities, amid efforts by Beijing to create a set of world-class research institutions.
The highest-rated European institution on the 2011 list was the Swiss Federal Institute of Technology Zurich, at 23rd. France's University of Paris XI came in 40th place and Pierre and Marie Curie University at 41.
The University of Tokyo, at 21st, was the highest-rated Asia-Pacific institution. China's own Hong Kong University and Tsinghua University were among the top 200, as was the National Taiwan University.
The rankings can be found at www.arwu.org.