But the survey's principal investigator, Dr Keith Johnson, said the performance in English was poor compared with other children whose mother tongue was not English, although they used it at school.

Singapore secondary students came top, scoring 534 points. Hong Kong pupils scored 427, just behind the Philippines on 430 points and just ahead of Nigeria on 401. Botswana was last on 330.

When reading skills were measured in the mother tongue, Finland came top for primary and secondary pupils. Hong Kong came ninth for primary pupils and eighth for secondary pupils.

Dr Johnson said Hong Kong students performed best when reading documentary texts such as advertisements and statistical tables in which there were limited complete sentences, and worst in narrative texts.

He believed the poor performance of students in English was related to teachers using a mix of English and Cantonese in schools which claimed to be English-medium schools.

He hoped the new policy of asking schools to make a clear decision on a medium of instruction by the next academic year would ease the problem.

The researchers' findings came as the Education Commission announced it would be asking employers, parents, teachers and students for their views on language proficiency.

The $1.5 million survey, believed to be the first of its kind in Hong Kong, will look at Cantonese, written Chinese, Putonghua and English.

The commission's Angela Cheung Wong Wan-yiu said the survey was aimed at discovering what helped or hindered students in acquiring language proficiency.

''The working group is looking for practical ways to maximise the supporting factors and minimise the frustrations involved in acquiring or, helping students to acquire, good language skills,'' she said.

Questionnaires will be sent to 8,050 people.

Results of the survey, to be conducted by a research team led by Hong Kong Polytechnic lecturers, are expected to be ready by June.