In recent months, the chief executive of Serum Institute of India, the world’s largest vaccine manufacturer, has come under increasingly intense pressure as both pro-government voices and leaders of the state governments headed by opposition politicians criticized him.

Some accused him for delays in supplying vaccines; some called him a “profiteer” for not offering Covid-19 vaccines to state governments at cost. There were calls for his company to be nationalized.

In an interview with The Times of London published on Saturday, the executive, Adar Poonawalla, described menacing calls from some of the most powerful men in India, creating an environment so ugly that he anticipated being out of the country for an extended period while he made plans to start producing vaccines elsewhere.

“‘Threats’ is an understatement,” Mr. Poonawalla said. “The level of expectation and aggression is really unprecedented.”

The interview reported that he had flown into London to join his wife and children hours before Britain barred travelers from India on April 23.

“I’m staying here an extended time, because I don’t want to go back to that situation,” he added. “Everything falls on my shoulders, but I can’t do it alone.”

The interview set off a storm on social media, with some interpreting his interest in manufacturing outside India as a threat to move his business and others seeing him as having been driven out of the country by the viciousness of his critics.

Within hours, Mr. Poonawalla wrote on Twitter that he would be returning to India “in a few days.”