BOSSES across the West of Scotland were bracing themselves for a "Black Monday" today as thousands of staff were hit by a winter flu virus.

The NHS 24 helpline has been swamped by thousands of calls since the New Year because of the respiratory bug.

But as many workplaces returned to normal today after the festive break, there were fears the scale of the outbreak would leave workplaces short-staffed.

The bug lasts seven to 10 days - much longer than a common cold - causing a cough and blocked sinuses. It has swept the country and there are particular fears for the elderly who may not be able to fight it.

Business leaders said its full impact would not be known until later today after most people were expected to have returned to work.

A spokesman for the Scottish Chamber of Commerce said: "We noticed in the run up to Christmas that a lot of people were going down with this.

"We haven't noticed anything exceptional in the past week because most businesses are not back yet.

"Most will be back today, so there is concern about what will happen. This bug does seem to be worse this year."

Up to 100,000 people have called NHS 24 while GPs have been inundated with an increase in the number of reported cases.

As many as four calls every three seconds were made during Hogmanay and New Year.

Many GPs, however, only returned to work midweek, leaving hospitals to cope with winter virus sufferers during the holiday.

Health boards across Scotland including NHS Greater Glasgow say they have been busier then usual.

A spokesman for health minister Andy Kerr said: "There has been an increase in the numbers of people needing hospital treatment due to respiratory problems.

"But hospitals are dealing well with the situation - there is no suggestion of any bed shortage."

A spokeswoman for NHS Greater Glasgow & Clyde today admitted they had been "extremely busy" but said "contingency plans were put in place" and everyone who needed admitted to hospital was admitted.

Alan Mitchell, assistant director of CBI Scotland said: "Businesses may have benefited because this has been going around during the holidays."