Colombo Torrington 60 Watta, Havelock Lane, and Dabare Road declared as isolated areas following the discovery of coronavirus patients.
Sri Lanka has seen a sudden surge in numbers of COVID19 patients in high-risk areas due to the newly-discovered 'cluster' in the military service.
Nearly 200 Navy officers have been tested positive with COVID19 thus far, bringing the countrywide total to 588.
Sri Lanka is expected to ease the lockdown in high-risk districts from May 04 onwards.