The World Health Organziation said on Monday that the B.1.617 variant first identified in India last year was being classified as a variant of global concern.
"We classify it as a variant of concern at a global level," Maria Van Kerkhove, WHO technical lead on Covid-19, told a briefing. "There is some available information to suggest increased transmissibility."
Indian coronavirus infections and deaths held close to record daily highs on Monday, increasing calls for the government of Prime Minister Narendra Modi to lock down the world's second-most populous country.
The WHO has said the predominant lineage of B.1.617 was first identified in India last December, although an earlier version was spotted in October 2020.
The variant has already spread to other countries, and many nations have moved to cut or restrict movements from India.
Van Kerkhove said more information about the variant and its three lineages would be made available on Tuesday.
WHO director-general Tedros Adhanom Ghebreyesus said that the WHO Foundation was launching a "Together for India" appeal to raise funds to purchase oxygen, medicines and protective equipment for health workers.