George Morrison, director of the university's Success for Life Programmes in Early Childhood Education, said trends in preschooling were shifting from play-based to setting learning and teaching standards.

He suggested Hong Kong could follow an assessment system used in Texas, including a list of academic standards designed for preschoolers to achieve and testing to check if the standards were being met.

The benchmarks require children to achieve a number of learning targets by the end of a school year, such as understanding texts in various genres (e.g. poetry and folk tales) and recognising and naming shapes.

If children are not harnessing the skills, teachers are accountable for devising ways to ensure they acquire them before leaving. A grading system certifies preschools with children who have met the standards. Professor Morrison said the idea of setting standards and using assessment was to 'get children ready for school'.

However, Julie Lam, principal of the Steiner preschool Highgate House, The Peak, said introducing tests in early childhood would be harmful to children.

'A lot of research shows testing children under the age of six creates undue pressure.'

Ms Lam said assessment advocates focused on its economic expediency but neglected the adverse psychological effects on children.

'Pushing children early on is desirable for politicians who want to plan improvements in the future economy. However, there are detrimental effects on the life of the child.

'A sense of failure and being put under pressure because of testing in these early years can contribute to low self-esteem in later life. Many suffer depression in adolescence because they failed to be successful in assessments at an early age.'

Ms Lam agreed it was important record children's progress, but pushing them to achieve standards was too harsh. 'It will deprive them of their joy in learning,' she said.

Ingrid Pramling Samuelsson, president of Omep (Organisation Mondiale pour l'Education Prescolaire), said it would be a 'catastrophe' if preschools were too busy working towards meeting standards.

'It's a disaster. I think we are on a way to an assessment-based society and that's crazy,' said the professor and co-ordinator for early childhood education at Sweden's Goteborg University.

'All creativity and freedom in teaching and learning will be lost,' Professor Pramling Samuelsson said.

She said it was important for children to learn how to interact and communicate from play-based programmes.

An educator from the Woodland Schools group, which runs three Montessori schools, agreed a heavy emphasis on academic performance put pressure on four-year-olds.

'Kindergarten is the only chance for children to play. Once they get into primary schools, they don't have the opportunity. There are lots and lots of tests and homework,' said Virginia Humpage, a senior curriculum co-ordinator at the group.

Ms Humpage said kindergartens needed to create a good environment for teachers to act as a facilitator, guiding pupils to explore.

'Children are creative ... They need play opportunities that allow them to learn through experimenting, through trials and through making mistakes,' she said.

During a public lecture held at Baptist University early this week, Professor Morrison defended his suggestion, saying his focus was not individual tests but continual observation of children's performance.

He said assessment did not necessarily involve 'paper and pencil' exams, and educators could achieve balance by using methods such as anecdotal assessment, class observation and collecting pupils' journals.

'Rather than relying on one single test, teachers must focus on ongoing assessment. This is a process to keep track on children's performance on a regular basis, say, weekly, monthly.'

Professor Morrison said his suggestion was not a rejection of play-based programmes but an effort to incorporate assessment.

'Most kindergartens around the world are using a play-based approach. But when we talk about play, we need set standards to define what is play, and to define what children should be learning through play.'