The exams authority is now re-marking all the remaining syllabus B oral papers in the Hong Kong Certificate of Education Exam.

But two further students at the school have now applied for re-marking of paper one, the writing paper, after their teacher found the grades of nearly a quarter of her class of 41 band one students were notably lower than expected.

Tang Chi-hung gained two Cs and an A in the other three papers in syllabus B, but an E in paper one, resulting in an overall grade of D. Ho Tsz-lung gained two Bs and a D in the other three sections and a D in paper one, giving an overall D.

Assistant English panel chair Florence Yip Yee-may has sent a written complaint to the Hong Kong Examinations and Assessment Authority about the 'unfair' marking of the paper.

She is demanding that the authority carries out a review of the marking scheme for paper one, remarks the scripts and gives a written explanation of its 'arbitrary' marking scheme.

'I believe about eight to 10 of my students were given marks that were too low in paper one,' she said.

'And at least five of my students were downgraded by one point in their overall grade in syllabus B because of their low scores in paper one.'

Ms Yip said instructions to students in the first question of paper one were to discuss the benefits and/or problems of holding a festival, but markers were told not to award good grades if pupils did not mention benefits and problems. For question three, students were instructed to write an imaginative story using a picture of a crocodile, yet markers had been told not to award good grades to candidates who wrote with too much imagination.

Ms Yip said several people who were markers for paper one had told her that they had been given the verbal instructions on question one and three by the chief examiner at a markers' preparation meeting held by the HKEAA.

The markers had noted the inconsistency between what they had been told and the instructions to candidates and one of them had pointed it out in written feedback on the meeting. The event had been for markers from across the territory.

Principal Yip Sau-wah said: 'I hope that the HKEAA will take this complaint very seriously and carry out a full investigation. I am asking for this review for the sake of fairness and justice for our students.'

A teacher who marks for paper one and asked not to be named said markers were given guidance in a written hand-out at the preparation meeting in June but it was very concise.

'Details were usually given in the verbal part,' she said. 'This is quite dangerous because different teachers understand it differently.'

A spokeswoman for the HKEAA said it would not comment on the performance of individual students as remarking of appeals was still taking place.

She denied that markers were given instructions to penalise candidates who did not mention both the benefits and problems of holding the festival or who wrote the crocodile story with too much imagination.'

Any accusation about students from a particular school being downgraded would be unfounded because scripts were assigned to markers at random so that each had scripts from several different schools, she added.