In November 2010, Nailya Babaeva, a Russian citizen in the US, allegedly applied for pregnancy benefits under Medicaid, a federally funded programme that is meant to help needy families get access to healthcare.

Ms Babaeva, who was pregnant with twins, lived in New York, where women can get immediate access to prenatal care under the programme based on a preliminary income assessment.

For her initial application to succeed, Ms Babaeva would have had to show that her household income was no more than $3,052 per month.

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According to a criminal indictment unsealed in New York earlier this week that includes details of the case, that’s exactly what she allegedly did, supplying in a letter signed by an employee at her husband Timur Salomatin’s workplace reporting his salary as $3,000 per month.

After their twins were born, a renewal application was allegedly filed around June 2011, claiming that Mr Salomatin’s pay had risen to $4,400. Ms Babaeva also claimed that she paid $500 per month in rent.

The truth, it is alleged, was that the house her family lived in was owned and paid for by her husband’s employer, and that, from at least June 2011 to December 2011, when Mr Salomatin’s employer deposited his pay directly in his bank account, he was being paid an average of $5,160 per month.

Earlier that year, in February, when Mr Salomatin took out a credit card, he is said to have told the bank his income was even higher at $8,333 a month.

What the indictment claims is that a number of Mr Salomatin’s colleagues and their spouses, 49 people in all, have followed the same general pattern – juicing benefits from Medicaid by underreporting their income, and then backing up the lies by producing letters from their place of work.

Where did they work? The Russian Mission to the United Nations, the Russian Federation Consulate General in New York or the local office of the Trade Representation of the Russian Federation in the USA.

All were diplomats or diplomatic spouses, people who are generally not allowed to access the benefits system except in emergencies.

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As US law enforcement officials tell it, the accused, 11 of whom remain inside the US, and a number of unnamed co-conspirators gamed the system to the tune of $1.5m.

While perpetrating the alleged fraud – the scheme is said to have run from 2004 to August this year – the defendants spent “tens of thousands of dollars on luxury items, including cruise vacations and purchases such as watches, shoes, and jewellery.”

Five are currently said to be working as diplomats at the Russian Mission, which declined to comment when contacted by The Independent on Friday. None, though, have been arrested, with the US Attorney for the Southern District of New York, Preet Bharara, saying this week that for that, the State Department would have to request a waiver of diplomatic immunity from Russia.

“Diplomacy should be about extending hands, not picking pockets in the host country,” Mr Bharara said as he announced the charges.

The allegations come at a tense time for US-Russia relations. In Moscow, the country’s deputy foreign minister, Sergei Ryabkov, told the state-backed news agency RIA Novosti that the complaints should have been pursued through diplomatic channels, not announced publicly.

“We have many complaints about US diplomats in Moscow, but we are not making them public,’’ he said, dismissing the charges as an attempt to take revenge for issues unrelated to bilateral relations between the two nations.

The US State Department said it did not expect the issue to harm diplomatic relations.