Hong Kong, Feb 20: The Sars virus which killed 299 people in Hong Kong may be spreading secretly in carriers who do not realise they have the disease, a news report said today. Tests on 400 blood donors in Hong Kong found two of them carried the Sars virus even though they had shown no symptoms of the disease, the South China Morning Post reported. University of Hong Kong microbiologist professor Yuen Kwok-Yung described the findings as ''very perplexing'' and a cause for concern, the newspaper said. ''The disease may be spreading in the community,'' he said. ''It (the survey) clearly shows there are antibodies in people who have never been symptomatic.'' However, he added that the survey also indicated that if carriers were not very symptomatic, they were also not very infectious. Hong Kong has not reported any fresh cases of Sars since last July following the outbreak which infected a total of 1,755 people in the former British colony. Bureau Report