The shots developed by UK-based drugmaker AstraZeneca and Oxford University are being manufactured at the Serum Institute of India, the world's biggest producer of vaccines, which has received orders from countries across the world.
The Indian government had held off exporting doses until it began its own domestic immunisation programme last weekend. Earlier this week, it sent free supplies to neighbouring countries including Bhutan, Maldives, Bangladesh and Nepal.
Foreign Secretary Harsh Vardhan Shringla said commercial supplies of the vaccine would begin from Friday in line with Prime Minister Narendra Modi's commitment that India's production capacities would be used for all of humanity to fight the pandemic.
"In keeping with this vision, we have responded positively to requests for supply of Indian manufactured vaccines from countries across the globe, starting with our neighbours," he said, referring to the free supplies.
"Supply of commercially contracted quantities will also commence from tomorrow, starting with Brazil and Morocco, followed by South Africa and Saudi Arabia," he added.
Brazil, which has world's second-highest COVID-19 death toll after the United States, has been urging India to send the AstraZeneca vaccine. It has agreed to take 2 million doses from Serum and was ready to send a plane last week to pick them up.
Morocco, South Africa and Saudi Arabia have also secured supplies from Serum, officials said.
(Reporting by Sanjeev Miglani; Editing by Pravin Char)
By Sanjeev Miglani