NEW DELHI — When voters swept Prime Minister Narendra Modi into power five years ago, it was in no small part because of his vows to create millions of jobs and vault India into an era of prosperity.

But now, just months before the next general election, Mr. Modi is facing a potentially troublesome challenge on the jobs promises that may be partly of his own making.

His government was accused on Thursday of suppressing an official report on the national unemployment rate that apparently showed it had reached a 45-year high in 2017.

The Business Standard, a respected Indian financial newspaper, published leaked findings from the unemployment report, which is based on a survey and produced by the National Sample Survey Office, a government agency.

There had been expectations that the report would be released in December. Two commissioners responsible for reviewing data in the report, who had advocated releasing it, resigned in protest this week.

Officials in Mr. Modi’s government scrambled on Thursday to blunt the impact of what amounted to withholding information that discredits the core of his economic record. The chairman of NITI Aayog, a government research organization, said the unemployment report was still in draft form, was not ready for dissemination and would be released in March. The response raised the possibility that the data could be revised.

But economists said the findings, if verified, were problematic for Mr. Modi, the dynamic prime minister whose popularity has always rested on his Hindu nationalism and promises to make India an economic powerhouse rivaling China.

While the leaked 2017 unemployment rate, 6.1 percent, may not sound so gloomy, it is roughly triple the rate of five years earlier, the last time a comparable national survey was conducted. And with India’s work force population of roughly 500 million, that translates into 30 million people who cannot find a job — including many of the 10 million to 12 million young people flooding into the labor market each year.

The rate also understates the true picture, partly because of the way India counts the number of employed. People who work irregularly — a couple of months on, a couple of months off — are considered employed unless they are jobless for a majority of the year.