The authority said 10 to 20 per cent of papers were marked by three - and sometimes four - teachers, because the variation of scores given by the first two was not in an acceptable range; normally, each liberal studies exam paper is marked twice.
This year, the two-paper liberal studies exam featured sensitive questions about the candlelight vigil on June 4 and China's territorial claims over the Diaoyu Islands. Such questions raised concerns among teachers and students, who thought they could be too political.
Christina Lee, general manager of HKEAA's Assessment Development, dismissed the claims and said those questions required students only to elaborate on how people see national identity. She said the number of papers needing to be marked more than twice were more or less the same as last year.
Methodist College student Ng Lok-yan said the grading was more objective and reliable than in the past, as a paper with widely differing marks from the first two markers could be reviewed twice more.
Janet Choi, from Sai Kung Sung Tsun Catholic School, however objected to the "national identity" questions, which she said had no right or wrong answers.
The HKEAA said 80,000 students sat this year's Hong Kong Diploma of Secondary Education examination. Of those, 10,973 were repeaters.
The authority said students taking at least three electives dropped by about 5,000, but 134 candidates took five electives. The spokesman said local universities usually considered only students' best two electives.