A major diplomatic row between the United States and India took a new turn Thursday as signs of a split emerged within the U.S. government over how to handle the case of an Indian diplomat and women’s rights advocate who was arrested in New York on charges stemming from the alleged exploitation of her nanny.

The Indian government, meanwhile, demanded that U.S. federal prosecutors drop their case against Devyani Khobragade, 39, India’s up-and-coming deputy consul general in New York and the mother of two young daughters.

As the dispute festered and outrage in India mounted over Khobragade’s arrest last week on visa fraud charges and her subsequent treatment by U.S. authorities, Secretary of State John F. Kerry made a conciliatory call to India’s national security adviser Wednesday and “expressed his regret” over the incident, according to the State Department.

But the Justice Department appeared to be taking a harder line. Preet Bharara, the Indian-born U.S. attorney in Manhattan who is prosecuting the case, issued a blistering statement denouncing “misinformation” about the charges against Khobragade and vowing to “uphold the rule of law, protect victims, and hold accountable anyone who breaks the law — no matter what their societal status and no matter how powerful, rich or connected they are.”

In a sharply worded retort Thursday, the Indian External Affairs Ministry said there was “only one victim in this case” — Khobragade, whose treatment it said violated the Vienna Convention and the normal courtesies due a diplomat. The ministry’s statement also blasted Bharara’s “remarks about equality before the law of both the rich and the poor,” saying that his “rhetorical” comment was “not conducive to resolving ‘inaccuracies.’ ”

Secretary of State John Kerry expressed regret to India amid controversy around the arrest of an Indian senior diplomat. (Reuters)

At a lunch with reporters in New Delhi on Thursday, Indian External Affairs Minister Salman Khurshid said that the criminal case against Khobragade should be dropped. He said he planned to speak to Kerry later in the day and would bring up the matter with him.

“We are not convinced that there is a legitimate legal ground for pursuing this case,” Khurshid said. Khobragade may not have paid her employee what she was owed, but that did not justify “treating her like a common criminal,” the minister said.

With tempers continuing to flare in India over the week-old dispute, small protests erupted in cities such as Kolkata and Hyderabad, where students chanted anti-American slogans and clutched signs that said, “Uncle Sam, don’t act ugly with India.”

The New Delhi government has demanded an unconditional apology for the arrest and has curtailed U.S. diplomats’ privileges and security measures in retaliation. And Indian officials announced they were transferring Khobragade to their country’s mission to the United Nations. The move, if approved, would give her full immunity from other charges going forward.

The Indian diplomat had already had prestigious postings in Pakistan, Italy and Germany. Last year, as she prepared for an assignment in pricey New York, she decided to hire a woman to accompany her, her husband and two daughters to perform child-care and housekeeping chores.

Khobragade thought she had found the right employee in a woman named Sangeeta Richard. U.S. labor rules required that the nanny be paid $9.75 an hour.

But U.S. authorities allege that Khobragade drew up two contracts — one with the proper amount and one with the actual amount to be paid (about $3.31 an hour for a 40-hour workweek, a wage that would often amount to much less because of longer hours worked).

Khobragade was dropping off one of her daughters at school last Thursday when agents of the U.S. Diplomatic Security Service arrested her.

Later, she was strip-searched and — she claims — cavity-searched by U.S. marshals; the Marshals Service is charged with housing federal prisoners. Experts said that was unheard-of treatment for a diplomat arrested by a friendly country. (A spokeswoman for the agency says that Khobragade was strip-searched, in accordance with standard procedures, but no cavity search was performed.)

In a statement issued Wednesday, Bharara said: “Khobragade was accorded courtesies well beyond what other defendants” typically receive. “She was not, as has been incorrectly reported, arrested in front of her children. The agents arrested her in the most discreet way possible, and unlike most defendants, she was not then handcuffed or restrained.”

The agents did not seize her cellphone, as is customary, let her make numerous calls from their car over a two-hour period “and even brought her coffee and offered to get her food,” the Manhattan U.S. attorney said.

The statement said Kobragade was “fully searched by a female deputy marshal — in a private setting . . . but this is standard practice for every defendant, rich or poor, American or not.”

Khobragade “clearly tried to evade U.S. law designed to protect from exploitation the domestic employees of diplomats and consular officers,” Bharara said. “Not only did she try to evade the law, but as further alleged, she caused the victim and her spouse to attest to false documents and be a part of her scheme to lie to U.S. government officials.”

He questioned whether any government “would not take action regarding false documents being submitted to it in order to bring immigrants into the country,” especially when the purpose of the alleged scheme “was to unfairly treat a domestic worker in ways that violate the law.”

He further wondered “why there is so much outrage about the alleged treatment of the Indian national accused of perpetrating these acts, but precious little outrage about the alleged treatment of the Indian victim and her spouse?”

Bharara noted that “there have been other public cases in the United States involving other countries, and some involving India, where the mistreatment of domestic workers by diplomats or consular officers was charged criminally.”

He said the second contract with the nanny, which “was not to be revealed to the U.S. government,” changed the payment to “far below minimum wage, deleted the required language protecting the victim from other forms of exploitation and abuse, and also deleted language that stated that Ms. Khobragade agreed to ‘abide by all Federal, state, and local laws in the U.S.’ ” Morever, he said without elaborating, “there are other facts regarding the treatment of the victim” that caused U.S. authorities to take legal action.

Bharara also sharply denounced what he described as legal retaliation against Richard’s family in India in attempts “to silence her” and to compel her to return to the country. As a result, he said, the family was brought to the United States.

“Some focus should perhaps be put on why it was necessary to evacuate the family and what actions were taken in India” against them, he said. The U.S. Attorney’s Office and the Justice Department “are compelled to make sure that victims, witnesses and their families are safe and secure while cases are pending,” he said.

In its reply, the Indian External Affairs Ministry said Bharara’s statement “incredibly . . . invites speculation about why it was necessary to evacuate the family of Ms. Richards and about the action purportedly being taken against them.” It denounced what it described as implicit criticism of the Indian legal system and law enforcement authorities and asked “what right a foreign government has to ‘evacuate’ Indian citizens from India while cases are pending against them.”

“When the legal process in another friendly and democratic country is interfered with in this manner, it not only amounts to interference but also raises the serious concern of calling into question the very legal system of that country,” the ministry said. It called the U.S. attorney’s statement “one more attempt at a post facto rationalization for an action that should never have taken place in the first instance.”

Khurshid, the external affairs minister, later dismissed Bharara in an interview with the news channel NDTV 24x7.

“As far as we’re concerned, we deal not with him, we deal with the State Department and deal with the secretary of state,” Khurshid said.

If found guilty of visa fraud and making false statements on a visa application, Khobragade could face 10 years in prison.

India’s national security adviser, Shivshankar Menon, has called Khobragade’s treatment “despicable and barbaric.”

Kerry, in his call with Menon, said he “empathizes with the sensitivities we are hearing from India,” a State Department statement said.

The secretary “understands very deeply the importance of enforcing our laws and protecting victims, and, like all officials in positions of responsibility inside the U.S. government, expects that laws will be followed by everyone here in our country,” it said. “It is also particularly important to Secretary Kerry that foreign diplomats serving in the United States are accorded respect and dignity just as we expect our own diplomats should receive overseas.”

At a briefing at the State Department, deputy spokeswoman Marie Harf would not characterize the conversation as an apology. She said the tone was “positive.”

Khobragade’s lawyer, Daniel N. Arshack, said the State Department seemed willing to resolve the case.

“I do believe, based on Secretary Kerry’s statement, that he has demonstrated an interest in having this case completely resolved,” Arshack said in an e-mail Thursday.

“The State Department’s acknowledgement of immunity will put an end to this matter once and for all,” he said.

Arshack said Wednesday that the diplomat actually had submitted one contract to the U.S. government, listing the proper salary for her domestic help, and had drawn up another with the woman, to deduct money from her pay to be sent to support her family in India.

Khobragade’s relationship with Richard grew troubled about six months after she started work. Arshack said the nanny asked whether she could work part time for other clients, and then stole items and later disappeared in June.

Branigin reported from Washington. Anne Gearan in Washington contributed to this report.