Director of the Department of Immunology and Molecular Medicine of Sri Jayewardenepura University Dr Chandima Jeewandara said this variant was detected in five samples obtained from the Dematagoda area in Colombo.
He said the variant was earlier detected on two occasions in Sri Lanka but from quarantine centers and not within the community.
Scientists say this Delta variant was spreading more quickly than the Alpha variant.
Sri Lanka is under a strict nationwide travel restriction which will be lifted on June 21 at 4 am local time.
Within the past two months, over 100,000 new infections have been reported as Sri Lanka has detected the new Delta and Alpha variants of the COVID-19 from quarantine centers and several areas, health officials said.
In an aim to bring down the infection rate, the government said it is planning to vaccinate at least 70 percent of its population by August or September this year.
