New Delhi, Dec 30 : Union Health Secretary Rajesh Bhushan has written to all the states and union territories asking them to curb crowding in the wake New Year celebration and keep a strict vigil on all events that could be a potential superspreader, the ministry said on Wednesday. A total of 107 samples have undergone genome sequencing till now, and as many as 20 people who have returned from the UK to India have tested positive for the new 'more infectious' coronavirus strain. On Tuesday, six patients were found to be infected with the mutant virus. These were the first cases to be reported by the country. "The Union Health Secretary has written to all the states to keep a strict vigil on all events that could be potential "superspreader" events, and to curb crowding in the wake of the New Year celebrations and various events associated with it as well as on-going winter season," the ministry said in a statement. The Ministry of Home Affairs has mandated that States and UTs, based on their assessment of the situation, may impose local restrictions with a view to contain the spread of Covid-19, such as night curfew. Drawing attention to this, the Health Secretary has urged the States to promptly assess the local situation and consider imposition of appropriate restrictions on December 30 and 31, 2020 as well as on January 1, 2021. Earlier today, the Centre extended the suspension of flights to and from the United Kingdom till January 7 amid alarm over the new highly contagious strain of the coronavirus. The decision was taken on the recommendations of a Joint Monitoring Group (JMG) headed by the Director General of Health Services (DGHS) and the National Task Force jointly headed by DG, ICMR and Member (Health), NITI Aayog. "It has also been suggested to Ministry of Civil Aviation that after January 7, 2021, strictly regulated resumption of limited number of flights originating from UK into India may be considered," the statement by the health ministry read. 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. Pursuant to announcement by British government, Indian government had taken cognisance of the reports of mutant variant and put in place a pro-active and preventive strategy to detect and contain the mutant variant. It included temporary suspension of all flights coming from UK with effect from the midnight of December 23 till 31. 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. Notably, the presence of the new UK Variant has already been reported by Denmark, Netherlands, Australia, Italy, Sweden, France, Spain, Switzerland, Germany, Canada, Japan, Lebanon and Singapore. /IANS