More than 100,000 children were absent from school with confirmed or suspected Covid infections last week – the highest number for England during the pandemic – after school reopenings triggered a surge in cases.

The figures from the Department for Education revealed that fewer than 92% of pupils were present in classrooms on 16 September, with 59,000 absent with confirmed cases of Covid-19 and a further 45,000 off with suspected cases.

Another 2,000 children missed school “due to attendance restrictions being in place to manage an outbreak,” according to the DfE.

The total of 103,000 with confirmed or suspected cases is higher than the number at the end of the last school year, a little more than two months ago. In mid-July the DfE said just 82,000 children were absent with confirmed or suspected cases.

The statistics are the first official signs of the spread of the virus within schools and colleges since the start of the new school year, when the use of preventive measures such as mask-wearing, social distancing and small group “bubbles” was halted by the DfE.

In July more than a million children were absent overall, but that included 930,000 children self-isolating because of classroom contacts. This year the DfE has ruled that children who are close contacts of confirmed or suspected cases do not need to self-isolate unless they also display symptoms.

Geoff Barton, the general secretary of the Association of School and College Leaders, said: “It is clear from the fact that over 100,000 pupils were absent from school last week with a confirmed or suspected case of coronavirus that educational disruption remains significant. We are hearing of schools where significant numbers of pupils are absent.

“We are hopeful that the vaccination programme for 12- to 15-year-olds will help to reduce this level of disruption. However, the government must also take more action to support schools and colleges.

“It should launch a public information campaign to encourage twice-weekly home-testing among pupils in the appropriate age groups, provide funding for high-quality ventilation systems in schools and colleges, and commit to providing more support if on-site testing is directed under the contingency framework.”

Barton also urged the government to publish its plans for 2022’s A-level and GCSE exams, saying it was “extremely frustrating” that guidance had still not been issued.

Nadhim Zahawi, the new education secretary, said it was “fantastic” to see more than 91% of children back in the classroom, compared with 87% at the same time last year.

“That’s down to the hard work of teachers, support staff as well as families whose efforts have been heroic in making sure children can get back to school safely,” he said.

“The rollout of the vaccine to those aged 12-15, which started this week, is another significant step in building the walls of protection from the virus across society.”