NEW DELHI — India has blocked a charity founded by Mother Teresa from accepting foreign donations for its humanitarian work.

It was not made clear why the government refused on Monday to renew the license of the organization, the Missionaries of Charity, under the country’s Foreign Contribution Regulation Act. The group can appeal, but for now, a major source of funding has been cut off.

The news came around a tense Christmas time, when churches have been vandalized and celebrations interrupted by hundreds of right-wing Hindus across the country.

The rise in attacks on Christians, who make up about 2 percent of India’s population, is part of a broader shift in which religious minorities feel less safe. Anti-Christian vigilantes are sweeping through villages, storming churches, burning Christian literature, attacking schools and assaulting worshipers. Right-wing Hindus have confronted Muslims during Friday prayers in the northern state of Haryana in recent months.

At a conference last week, hundreds of right-wing Hindu monks openly called for Muslims to be killed, in their quest to turn India, constitutionally a secular republic, into a Hindu nation.

In October, Prime Minister Narendra Modi invited Pope Francis to visit India, home to one of Asia’s oldest and largest Christian populations. But it remains to be seen if the government’s latest move to cut off the Christian charity’s foreign funding will complicate that invitation.

Under Mr. Modi’s government, India has also been tightening rules on foreign funding of nongovernmental organizations. It has placed restrictions on many Christian and Muslim nonprofits and put others on a watch list for violating Indian laws, especially the laws concerning religious conversions.

Nonprofits are required to file detailed financial statements of their foreign funds and how they use them in India and are restricted from receiving those funds until their licenses are approved by the government.

Last year, the human rights organization Amnesty International shut its India operations in response to a series of government reprisals including the freezing of its bank accounts. The government said at the time that the organization repeatedly violated local laws by circumventing the regulations under which foreign entities can receive donations from abroad.

Sunita Kumar, a spokeswoman for the Missionaries of Charity in the eastern city of Kolkata, where it is based, expressed confidence on Tuesday that the licensing issue could be resolved. She said the charity’s work would not be affected immediately, though it gets a large chunk of its income from overseas donors.

“There’s enough locally also that’s given, so we can handle that,” she said, without explaining how long it would be able to sustain its work with only local donations.

According to government filings, foreign donations accounted for over $13 million of the charity’s income in the financial year that ended March 2021. It was not clear what percentage of the total that is, since the charity does not reveal that figure.

Mother Teresa, a Roman Catholic nun, founded the Missionaries of Charity in 1950. She was awarded the Nobel Peace Prize in 1979 in recognition of her work caring for the poor and the sick, and declared a saint in 2016, nine years after her death.

The nonprofit provides critical care and medical infrastructure in a country where, even before the pandemic, the health system has struggled to keep up with the growing needs of its 1.4 billion people. India’s devastating second wave of the coronavirus killed hundreds of thousands of people.

This month, the police in the western state of Gujarat said they were investigating a complaint against the charity for forcing girls in a shelter home to read the Bible and wear a cross — accusations that Ms. Kumar, the charity’s spokeswoman, rejected.

“I’ve worked here for 45 years, and nothing like that has ever happened,” she said.

On Monday, opposition leaders criticized the government’s decision.

“This is indeed shocking,” said Shashi Tharoor, a member of Parliament from the southern state of Kerala of the main opposition party, the Indian National Congress, on Twitter. “When Mother Teresa wins a Nobel Prize, India rejoices. When her organization serves the poor and destitute, the government cuts off their funding.”