Fifteen-year-olds here experience more bullying than their peers in 50 other countries and economies, and only the children of Latvia and New Zealand have it worse, said a study by the Organisation for Economic Cooperation and Development (OECD).

The findings were released in the third volume of data from the Programme for International Student Assessment (Pisa), a three-yearly study run by the OECD.

In the study conducted in 2015, students were asked to report how frequently they were exposed to six different types of bullying according to a four-point scale, ranging from "never or almost never" to "once a week or more". The six categories were: being left out, made fun of, threatened, property taken by other students, being hit or pushed around, and having nasty rumours spread about them. They measured physical, verbal and relational bullying, like social exclusion.

The countries were ranked according to an index based on an aggregate of the responses. Britain was sixth-worst, Finland was 14th and Hong Kong 16th. The least bullying was reported in South Korea.

In Singapore, 5,825 students, randomly selected from 168 public schools, and 290 students from nine private schools, took the computer-based test.

The most common form of bullying experienced by students here was being made fun of by other students, with 18.3 per cent saying they experienced this at least a few times a month. The OECD average was 10.9 per cent.

Related Story Singapore students suffer from high levels of anxiety: Study

Related Story Bullying in schools being monitored closely: MOE

This was followed by 11.9 per cent saying they were left out of things on purpose at least a few times a month, compared with the OECD average of 7.2 per cent.

Close to 9 per cent said others had spread nasty rumours about them at a similar frequency. Those who were hit or pushed around by others, or had belongings taken away or destroyed at least a few times a month, made up 5.1 per cent, while 4.4 per cent said they were threatened by other students at the same frequency. Singapore also had 14.5 per cent of students who described being frequently bullied, compared with the OECD average of 8.9 per cent.

The Pisa study suggested that in Singapore, bullying could be more frequent in schools where teachers were perceived as being unfair, and where schools have a poor disciplinary climate, causing students to be more likely to engage in high-risk behaviour.

Teachers who are seen as unfair may humiliate students or undermine their self-confidence, and these students then try to assert their superiority over vulnerable groups to regain their confidence.