Twenty-one Indian-origin persons have been sentenced in Washington to up to 20 years for their role in a massive India-based call centre scam which defrauded thousands of US residents of hundreds of millions of dollars, the Justice Department said.

Washington: Twenty-one Indian-origin persons have been sentenced in Washington to up to 20 years for their role in a massive India-based call centre scam which defrauded thousands of US residents of hundreds of millions of dollars, the Justice Department said.

The sentences which range from 4 years to 20 years were announced earlier this week, the department said in a press release on Friday.

"The stiff sentences imposed this week represent the culmination of the first-ever large-scale, multi-jurisdiction prosecution targeting the India call center scam industry," said Attorney General Jeff Sessions.

"This case represents one of the most significant victories to date in our continuing efforts to combat elder fraud and the victimisation of the most vulnerable members of the US public.

"The transnational criminal ring of fraudsters and money launderers who conspired to bilk older Americans, legal immigrants and many others out of their life savings, must recognize that all resources will be deployed to shut down these telefraud schemes, put those responsible in jail and bring a measure of justice to the victims," Sessions said.

According to various admissions made in connection with the defendants' guilty pleas, between 2012 and 2016, the defendants and their conspirators perpetrated a complex fraud and money laundering scheme in which individuals from call centres located in Ahmedabad frequently impersonated officials from the federal tax agency, Internal Revenue Service (IRS) or US Citizenship and Immigration Services in a ruse designed to defraud victims located throughout the US.

Using information obtained from data brokers and other sources, the accused targeted the US victims who were threatened with arrest, imprisonment, fines or deportation if they did not pay alleged monies owed to the government.

Victims who agreed to pay the scammers were instructed how to provide payment, including by purchasing stored value cards or wiring money. Upon payment, the call centres would immediately turn to a network of "runners" based in the US to liquidate and launder the fraudulently obtained funds.

For their services, the runners would earn a specific fee or a percentage of the funds. Runners also received victims' funds via wire transfers, which were retrieved under fake names and through the use of using false identification documents, direct bank deposits by victims or other gift cards that victims purchased.

Three other conspirators were sentenced earlier this year for laundering proceeds for the conspiracy.

Twenty-two of the accused were held jointly and severally liable for restitution of $8,970,396 payable to identified victims of their crimes. Additionally, the court entered individual preliminary orders of forfeiture against the defendants for assets that were seized in the case, and money judgments totalling over $72,942,300.

The indictment in the case also charged 32 India-based conspirators and five India-based call centres with general conspiracy, wire fraud conspiracy, and money laundering conspiracy. These defendants are yet to be arraigned in the case.