Countries with class sizes smaller than the UK may find it easier to comply with social distancing restrictions amid Covid-19, a report suggests.

Primary schools in the UK have an average of 27 pupils in a class, according to the Organisation for Economic Co-operation and Development’s (OECD) latest Education At A Glance study.

The average class size across OECD countries is 21 children.

The report, which looks at the state of education systems across 37 nations with developed economies, plus nine other countries, ranks the UK as having the fourth highest number of pupils per class.

Only Chile, Japan and Israel have more students on average in a primary school class than the UK.

The report comes as dozens of schools across the UK have been hit with coronavirus cases since pupils returned to class over the past week.

Some schools have closed their doors just days after reopening, while others have told whole classes and year groups to self-isolate for two weeks following confirmed cases.

In June, primary school class sizes in England were capped at 15 pupils to reduce interactions between children, but now schools have been told to keep children in class or year-sized “bubbles”.

The OECD report said: “Ensuring a minimum safety distance between pupils and staff will depend on many factors, such as classroom size, room availability, and the number of students per class.

“Countries with smaller class sizes may find it easier to comply with new restrictions on social distancing, provided they have the space to accommodate the number of students safely.”

The OECD report also warned that the pandemic may have a “severe impact” on UK universities which rely heavily on international students, who pay higher tuition fees than domestic students.

It warns: “The crisis may have a severe impact on the internationalisation of higher education, as the delivery of online course material and travel restrictions may raise questions among international students’ perception on the value of obtaining their degree from a foreign institution.

“The United Kingdom, which accounts for 8% of the market share for international tertiary students, may be more strongly affected, although its new student visa policy and blended learning concessions may mitigate declines to an extent.”

One in five doctoral students come from abroad on average across OECD countries, but the share is more than 40% in the UK.

The study adds: “Some countries, such as Australia, New Zealand and the United Kingdom, have also reduced barriers to the migration of highly qualified students, facilitating their entry into the labour market after graduation.

“A decline in international student mobility in these countries risks affecting productivity in advanced sectors related to innovation and research in the coming years”.

On the findings on class sizes, Paul Whiteman, general secretary of schools leaders’ union NAHT, said: “It is difficult to get away from the view that our classes are too large compared to other countries.

“The fact is, coronavirus will be a challenge for every school system, regardless of their average class size.

“Success will not be determined by class size alone. What’s needed is effective safety measures with sufficient funding so that schools can implement them, clear government guidance, and support for schools rather than sanction when they come up against inevitable problems.”