New Delhi, April 5 : National carrier Air India has brought in 21 tons of critical medical supplies from China for treatment of coronavirus infected people. "On the international front, the Ministry of Civil Aviation and Air India have worked closely with China to establish a cargo air-bridge between the two countries for transfer of critical medical supplies. The first cargo flight between India and China was operated by Air India on 4 April 2020, carrying 21 tons of critical medical supplies from China," an official statement said. It also said that the a total of 116 flights have been operated under 'Lifeline Udan' so far by Air India, Alliance Air, the IAF, Pawan Hans and private carriers. Out of the total, 79 flights have been operated by Air India and Alliance Air. Total cargo transported till April 4 is around 161 tons, it added. The cargo includes Covid-19 related reagents, enzymes, medical equipment, testing kits, personal protective equipment (PPE), masks, gloves, other materials of HLL and ICMR along with cargo requisitioned by state government and union territories and postal packets among others. Bulk of the cargo comprises light-weight and voluminous products like masks, gloves and other consumables, that require more space on the aircraft per ton. Special permission has been taken to store cargo in the passenger seating area and overhead cabins, with due precautions, the statement said. Lifeline Udan flights operate in a 'hub and spoke' model. Cargo hubs have been established at Delhi, Mumbai, Chennai, Kolkata, Hyderabad and Bengaluru. Lifeline Udan flights connect these hubs to locations like Guwahati, Dibrugarh, Agartala, Aizwal, Dimapur, Imphal, Coimbatore, Thiruvananthapuram, Bhubaneswar, Raipur, Ranchi, Srinagar, Port Blair, Cochin, Vijayawada and Panaji. The statement also said that domestic cargo operators SpiceJet, Blue Dart and Indigo are operating cargo flights on a commercial basis. /IANS