Health officials have launched an investigation into why thousands of women in Scotland are failing to take up potentially life-saving cancer tests.

The number having smear tests fell by more than 5% in the final quarter of last year compared with the previous three months.

Traditionally, there is a drop as Christmas approaches and the figures usually rise again after New Year. But the number of samples sent to laboratories between October and December 2006 is also down by 2.7% - or more than 2500.

The data comes days after The Herald revealed concern among doctors about the computerisation of the screening system next month.

Calls for the launch to be delayed will be put to GPs at a British Medical Association conference later this week.

Carol Colquhoun, national screening programmes co-ordinator, said the Breast and Cervical National Advisory Group was researching the reasons for the dip in uptake of smear tests in recent years.

One theory is a new NHS leaflet which describes the limitations as well as the benefits of the checks has put off some patients.

It is also thought publicity about a new vaccine against the disease may have given some people the wrong message that screening is no longer important.

Ms Colquhoun said: "We wish to encourage women to attend because we know cervical screening actually has an impact on reducing deaths from cervical cancer and incidence of cervical cancer."

The possibility of including information about smear tests in sex education classes at school is being considered by the advisory group.

Ms Colquhoun added: "We know that women in younger age brackets are not attending as well for cervical smears."

Letters will be issued to female patients from a central bureau under the new national system for organising the smear programme.

GP surgeries will no longer send off forms with samples, instead typing details into a computer database and printing off labels. Results will be communicated to surgeries electronically.

Officials say this process will be safer and more efficient.