Hong Kong once again has three universities in the world's top 50, with two more narrowly missing the cut, organisers of the QS World University Rankings revealed on Wednesday.

Both the University of Hong Kong and the Chinese University ranked higher than ever before, while the Hong Kong University of Science and Technology returned to the top 50.

HKU was up nine places at seventeenth overall while CUHK climbed eleven places to 36th in the world. Meanwhile UST rose 13 places, ranking 47th.

The ranking is based on a study of 1,500 universities around the world. Evaluators consider nine indicators, including academic reputation, what employers think of an institution, the ratio of students to faculty and whether the university has many international students, staff and global networks.

CUHK saw its scores improve in most areas, most notably sustainability, where it finished 132 places higher than last year.

The university said in a statement that it is highly regarded for its environmental concepts and leadership in creating and applying sustainable development solutions.

CUHK also earned a perfect score for its ratio of international faculty and a high score for academic citations.

Its president, Rocky Tuan, said the results demonstrate CUHK's commitment to academic excellence and ability to compete with world-class universities.

Meanwhile, HKUST said that despite being a newer institution, its embraces innovative teaching methods and resources that adapt to evolving societal need.

It said it was making the most of new technologies like artificial intelligence to enhance student learning and promote the SAR's goal of becoming an international innovation and technology centre.

The Hong Kong Polytechnic University ranked 57th, continuing a climb in recent years, while City University was 62nd. Two other local universities were also ranked: Baptist University was placed joint 252nd while Lingnan University was in the 711-720 band.

The Massachusetts Institute of Technology was first overall, ahead of Imperial College London and Oxford University. The National University of Singapore ranked best in Asia and eighth overall. Peking University was China's best, finishing 14th in the world.