NEW YORK — Federal law-enforcement authorities have charged nearly 50 past or present Russian diplomats and their spouses in a $1.5 million Medicaid fraud scheme.

An 18-month FBI investigation revealed “the systemic fraudulent submission of falsified applications for Medicaid benefits” by the diplomats and their spouses, according to a criminal complaint made public Thursday in U.S. District Court in Manhattan.

The diplomats and their spouses obtained the benefits for pregnancies, births and first-year-of-life medical needs, generally applying at the same New York hospital, which was not identified, the complaint says.

“Diplomacy should be about extending hands, not picking pockets in the host country,” said Preet Bharara, the U.S. attorney for the Southern District of New York, who, along with George Venizelos, head of the New York office of the FBI, detailed the charges at a news conference.

Bharara said 25 current and former diplomats and 24 spouses were criminally charged after they underreported incomes to qualify for Medicaid funds even as they spent tens of thousands of dollars on luxury vacations, concert tickets, fine clothing and helicopter rides.

No arrests were made and only 11 of the diplomats and their spouses remain in the United States. The case is unlikely to go to trial because the defendants have immunity, Bharara acknowledged.

But he noted the State Department could seek a waiver of immunity from the Russian government to allow a prosecution to go forward.

Of the 63 births to Russian diplomats and their spouses in New York City between 2004 and 2013, 58 were paid for by Medicaid, a health-care program for the poor, the complaint says.

At the same time, the same people were buying jewelry, watches, clothes and shoes at such high-end retailers as Jimmy Choo, Prada, Burberry, Tiffany and Bloomingdale’s, according to the complaint.

The diplomats and spouses are present or past workers at such offices as the Russian Mission to the United Nations and the Russian Consulate.

Charges in the criminal complaint included conspiracy to commit health-care fraud and conspiracy to steal government funds and make false statements relating to health-care matters.

Russia’s Deputy Foreign Minister Sergei Ryabkov said in remarks carried by the Interfax news agency in Moscow that “we are bewildered” that the U.S. government publicized the charges before speaking to the Russian government.

He dismissed the charges as “no more than a cheap spin effort, no more than a desire to fulfill the order of Russophobic forces in the United States.”

Material from The Associated Press is included in this report.