South Africa has asked the Serum Institute of India to take back the one million Covid-19 vaccine doses the company had sent in early February, The Economic Times reported, a week after the country said it will put on hold use of AstraZeneca's shot in its vaccination programme.

Serum Institute of India, which is producing AstraZeneca's shot, has emerged as a key vaccine supplier.

One million doses of the Covid-19 vaccine landed in South Africa last week and another 500,000 were due to arrive in the next few weeks.

The company did not immediately respond to a Reuters request for comment.