New Delhi, Jan 1 : The central government on Friday said that four more cases of the mutant Covid UK strain have been detected in the country, taking the total tally of such cases to 29 so far. They are kept in physical isolation in health facilities. Out of these 29 cases, eight have been registered at National Centre for Disease Control in Delhi, two at CSIR Institute of Genomics and Integrative Biology in Delhi, 10 at National Institute of Mental Health and Neuro-Sciences in Bangalore. Three such cases have been detected at Cellular and Molecular Biology in Hyderabad, five at National Institute of Mental Health and Neuro-Sciences in Bangalore, and one at National Institute of Biomedical Genomics in West Bengal. On Tuesday, a total of six UK returnees were found to be positive with the new variant genome. These were the first cases to be reported by the country that has the second highest number of cases after the United States. The British Government had recently announced that the newly identified strain of the virus found in their population is up to 70 per cent more transmissible. Notably, the new UK variant has already been reported by Denmark, Netherlands, Australia, Italy, Sweden, France, Spain, Switzerland, Germany, Canada, Japan, Lebanon and Singapore. From November 25 to December 23 midnight, about 33,000 passengers disembarked at various Indian airports from UK. All these passengers are being tracked and subjected by states and UTs to RT-PCR tests. /IANS