Companies are being warned they could face staff absenteeism of up to 25 per cent as a consequence of a Swine flu escalation.

The alert comes as NHS bosses have drawn up plans to reduce the impact of swine flu on key services as the number of cases begin to surge.

Dr Peter Elton, Director of Public Health for NHS Bury, has disclosed that, after falling for several weeks, the number of new swine flu cases has started to rise nationally. He said: “It has almost doubled since the schools returned, and the number of people getting swine flu is likely to increase over the next few weeks.

“It is anticipated that the swine flu vaccination will become available during October. It will be offered to people at highest risk of harm from swine flu. We hope to be in a position to offer it to school children as soon as we are able.”

Justin Kelly, head of employment law at Bury solicitors Butcher and Barlow, is advising firms to take pre-emptive action to protect their workforce and prevent significant financial loss.

He said: “Company heads should be putting together contingency plans, reviewing their sickness and hygiene policies and briefing employees to prepare for the worst. Businesses must face up to the very real possibility that they could lose 25 per cent of their workforce and consider how they will continue to operate under those circumstances.”

Mr Kelly, a partner at the Bank Street firm, added: “Swine flu has the potential to be very damaging. But if employers act now rather than burying their heads in the sand, they can minimise that threat.”