A probe into soaring staff sickness levels at Birmingham City Council has found that absenteeism plunges in August – in time for workers to take their holidays.

Last December, annual illness absence rates for city workers hits an average 12.5 days.

But each year at the height of the holiday season, the figure falls to about six days per person, according to deputy council leader Paul Tilsley.

Coun Tilsley (Lib Dem Sheldon) told a cabinet meeting: “Sickness statistics drop in August, but they tend to be high during the rest of the year.

“I can’t understand that.”

Asked if the sharp fall could be connected to the holiday season, Coun Tilsley replied: “You might have a point”.

The variation emerged following an investigation into the long-running staff sickness problem.

With so many people away from their desks at any given time, the council is failing to deliver on a promise to respond to complaints from the public within 10 days.

Replies were sent out on time in only 78 per cent of cases at the end of 2009, against a target of 90 per cent.

Coun Tilsley admitted: “The way we manage our complaints procedure, if an individual officer dealing with the matter is off, the complaint doesn’t get replied to.”

A six-year management campaign to cut absenteeism has failed to have much impact, with the council consistently failing to hit a target of 9.25 sick days per employee.

Coun Tilsley vowed to use new technology to “drill down” into the reasons for sickness on such a scale and to draw up new strategies for curbing absenteeism.

New IT systems installed as part of a multi-million pound business transformation project will allow human resources officers immediate access to the day to day employment records of 25,000 council staff.

Coun Tilsley added: “We are now able to study such detailed information that we can really start to find out why sickness is such a problem. We have to work out why it is so difficult to meet these targets.”