Staff absenteeism due to coughs, colds and flu-like symptoms is 66% higher than for the same period last year.

The news came as ministers warned that swine flu cases could soon hit 100,000 a day by the end of next month, and a 19-year-old became the fourth victim of the outbreak.

The last week in June saw one in every 400 employees calling in sick with a cough, cold or flu-like symptoms. The annual average for June is around one in every 630 employees.

The figures are provided by absence management company FirstCare, which provides real-time data based on company records.

FirstCare chief executive Aaron Ross linked the rise in sickness levels to the swine flu pandemic: “Time really is beginning to run out for employers, swine flu is a pandemic and should be treated as such. Cases of H1N1 swine flu across the UK are likely to increase further with the onset of autumn, so employers should put plans in place now in order to cope with possible increases in absence levels in September and October.”