The Irish Cancer Society says it is disappointed that it could take three years to roll out the first phase of the bowel screening programme.
Minister for Health James Reilly has said that, as promised, the programme will commence on a phased basis during the final quarter of this year.
It will initially target men and women aged 60 to 69; an estimated 500,000 people.
Live testing of the programme is under way to ensure all systems are operating effectively.
Last week, the minister told the Dáil it was anticipated that this first phase will take up to three years to complete.
This is due to the need to build up capacity in colonoscopy services around the country to deal with referrals.
15 candidate colonoscopy units have been identified around the country to support the screening programme and these have to secure accreditation.
The ICS said today that while it welcomed the roll-out of the much-needed screening programme, it was concerned about the timescale to roll-out the programme and what could be done to speed it up.
When fully implemented, it will see screening extended to people aged 55 to 74 years.
It will offer free screening to people within the age groups every two years.
Over 2,000 new cases of bowel cancer are diagnosed in Ireland each year and the number diagnosed is expected to increase in the future.