The Movement has records of around 9,000 to 10,000 patients, says its director Dr. Gamini Seneviratne.
However, the WHO estimates the figure at around 14,000.
Dr. Seneviratne said they would start clinics to search for the unreported TB patients, including at prisons, in the estates and urban slums etc.
He advised the public to obtain immediate medical treatment if coughing and mild fever lasts for more than two weeks.
TB is determined by a sputum test, and can be cured by medication.