Hong Kong's schools reopened on Monday morning for a delayed start to the academic year, after last week's typhoon warning forced the cancellation of the first day of term.

Five schools are starting the year with no government-funded primary one classes after failing to attract the required 16 pupils, putting them at risk of closure in future.

Confucian Tai Shing Primary School in Wong Tai Sin got round the problem by introducing a private primary one class with the Education Bureau's approval, eventually enrolling 18 pupils.

A parent of a pupil there said he was not worried about the prospect of closures, and private education may be good for his child.

"If you've got a smaller class group, it's better for a child anyway because he can learn more, and learn quicker," the man told RTHK.

The school's principal said the fact that Wong Tai Sin has an ageing population is a key reason for the difficulties in enrolling pupils, but her school is now applying to go fully private.

"We can be more flexible... When we were getting ready to transform into a private school, we hired more foreign teachers," Yuen Poon Suk-Han said.

"This is attractive for some parents as this may provide a better English learning environment for pupils. Some non-local pupils may have fewer worries when joining our school as well."

Education Secretary Christine Choi said the government is working hard to deal with the effects that a declining number of children are having on the territory's schools, including by merging schools and cutting the number of classes.

"The shrinking number of pupils is a structural problem and it is within our expectations. Of course, we hope students' learning will not be affected, but at the same time, we have to ensure that public money is well-used," she said.