Chennai, Nov 27 : The Tamil Nadu government has directed to intensify screening at Chennai international airport and other airports in the state after the Union Health Ministry issued an alert on the risk posed by a new Covid-19 variant. State health minister Ma Subramanian told IANS, "We have received an alert from the Union Health ministry following which the state health secretary issued directives to all district collectors to act according to the guidelines. This includes testing of travelers from certain countries as well as following Covid-19 protocols. Travelers from Botswana, South Africa and Hongkong will have to mandatorily undergo tests and if necessary quarantine." State health secretary J. Radhakrishnan in a statement said that it was Tamil Nadu, the first state that made RT-PCR test negative report mandatory for travelers from any country. He said that for countries like South Africa, Botswana and Hongkong, testing on arrival is mandatory and RT-PCR tests will be tightened through the Directorate of Public Health and Preventive Medicine. The state health department has also commenced testing passengers traveling into the state from Singapore, Brazil, China, Mauritius, Bangladesh, and New Zealand in addition to Botswana, South Africa and Hong Kong. /IANS