A further 10 patients in England, including three children, have been confirmed with swine flu, bringing the total number of confirmed cases in the UK to 65, the Health Protection Agency said today.

The cases are in the east, the north-west, the south-east and London. Five of the patients had returned from travel abroad, four were in close contact with previously confirmed cases and the last case is under investigation as to the source of the infection. All patients are recovering at home, the HPA said. Some 370 cases are under investigation.

In other developments, four schools closed after pupils contracted swine flu reopened in time for the exam season. The affected schools, two in London and two in south-west England, shut their doors to pupils last week as a precaution but were allowed to open again today.

Three of them – Alleyn's School in Dulwich, south-east London, Paignton Community and Sports College in Devon, and Downend School in South Gloucestershire – are secondary schools with pupils sitting GCSEs and A-levels this summer. The private preparatory Dolphin School in Battersea, south-west London, also returned to normal this morning.

Even as they reopened, another school closed for a week from today after one of its pupils was diagnosed with influenza A. Hampton School, an independent boys' school in south-west London, said the case was not yet confirmed as swine flu but further tests were being carried out and the first year pupil was recovering well at home.

Exams at the school, which has more than 1,000 boys aged 11-18, will continue as normal.

A small number of GCSEs have already taken place, but most of the exams get under way this week.

The private Alleyn's School, which closed on 4 May when five Year 7 pupils were confirmed with the disease, said all staff and pupils who had not developed infections and were symptom-free could return to the £13,437-a-year school.

Senior deputy head Antony Faccinello said the school was in close contact with the exam boards and had already made arrangements to put back some oral and practical exams. Staff put a large amount of teaching material on the school's website last week and teachers are also offering optional extra lessons.

Faccinello said the impact of the closure on students sitting GCSEs and A-levels was expected to be minimal.

"Some people take the view that most courses last two years and this is a week at the end. I think a lot of it is about reassuring people," he said.

Of the cases in the UK, 60 are in England and five are in Scotland.