UK nationals visiting India this month will have to undergo mandatory quarantine even if they are fully vaccinated against COVID-19 in retaliation for UK curbs on Indian citizens.
The new rules, which take effect from Monday, follow the UK decision to require Indians vaccinated with AstraZeneca's Covishield to quarantine.
India mainly relies on the Covishield vaccine, developed by AstraZeneca and manufactured in India by Pune-based Serum Institute, which is not recognised by Britain under new rules, despite being identical to the doses given to millions of Britons.
AstraZeneca is one of the key providers to Britain's vaccination programme, along with US peers Moderna and Pfizer.
"India has decided to impose reciprocity on UK nationals arriving in India from the UK," the source said, declining to be identified in line with government policy.
Government sources in New Delhi had last month warned of retaliation after Foreign Minister Subrahmanyam Jaishankar said he had urged for an early resolution after a meeting with his British counterpart at the United Nations General Assembly in New York.
Iran and the United States agreed to halt recent hostilities in the Gulf and renew talks regarding their dispute over the Strait of Hormuz, a US official said on Sunday, raising hopes of saving an interim peace deal that was under pressure from days of tit-for-tat strikes.
Pakistan's security forces killed at least 29 militants in ground and air operations along the Afghanistan border, it said on Monday, while the Afghan Taliban said at least 38 civilians were killed in airstrikes.
Russian President Vladimir Putin says Moscow will continue its military push to fully capture four Ukrainian regions, rejecting what he described as a Ukrainian proposal to scale back long-range attacks.
Ousted former Prime Minister Sheikh Hasina has vowed to return to Bangladesh this year, brushing aside a death sentence handed down in absentia and denouncing the ruling as "illegal, unconstitutional and politically motivated".