US law enforcement officials have admitted a female Indian diplomat was strip-searched after she was arrested last week.
The case has sparked fury and fierce reprisals from India.
Amid a growing row, New Delhi is taking a series of measures against US diplomats in the country after the New York arrest on Thursday of deputy consular general, Devyani Khobragade.
India has described her arrest – while she was dropping her children off at school – as humiliating.
The Indian government retaliated by ordering a range of measures including the return of identity cards for US consular officials that speed up travel into and through India, New Delhi foreign ministry sources said.
Indian security forces also removed barricades outside the US embassy in New Delhi, raising fears for the safety of personnel.
State Department deputy spokeswoman Marie Harf urged the Indian government to uphold all its obligations to protect US diplomats in the country.
Ms Khobragade was detained for allegedly underpaying her domestic helper, who is also an Indian national, and for lying on the helper’s visa application form.
She was released on a bond the same day.
When asked if Ms Khobragade was strip-searched, the US Marshals Service (USMS) said she “was subject to the same search procedures as other USMS arrestees held within the general prisoner population in the Southern District of New York”.
Ms Harf admitted it was a “sensitive issue” but insisted it was a “separate and isolated incident” that should not “be tied together” and allowed to affect broader US-Indian ties.
“Thus far all indications are that appropriate procedures were followed,” Ms Harf told journalists. “But nonetheless … we understand this is a very sensitive issue, and we’re continuing to review exactly what transpired.”
Ms Harf also revealed that the State Department had written to the Indian embassy in September to warn them “of allegations of abuse made by an Indian national against the deputy consular general of India in New York”.
The case is the latest involving alleged mistreatment of domestic workers by wealthy Indian families. Many are poorly paid in India and rights groups regularly report cases of beating and other abuse.
“The United States and India enjoy a broad and deep friendship, and this isolated episode is not indicative of the close and mutually respectful ties we share,” Ms Harf said in an earlier statement.