"I said I wouldn't comment on the underlying substance because it is an ongoing law enforcement matter and it would be inappropriate for me to do so when DOJ (US Department of Justice) is presenting a case in court. I also made clear that we have noted at the most senior levels of this government, the Secretary of State has raised this directly with his foreign counterpart that we take this issue very seriously," said Miller, while speaking at a media briefing in Washington DC on Tuesday.

"They told us they would conduct an investigation. They have publicly announced an investigation and now we'll wait to see the results of the investigation. It's something we take very seriously," he said.

The statement by Miller comes at a time when an indictment has been unsealed by the US Justice Department against an Indian national who has been accused of allegedly being involved in a foiled plan to assassinate a leader of the Sikh Separatist Movement, who is based in the US and is a citizen in New York. It is believed that the target of the foiled assassination plot was Khalistani terrorist and leader of the banned Sikhs For Justice (SFJ) outfit Gurpatwant Singh Pannun.

The Justice Department said that an Indian national named Nikhil Gupta was working for an Indian government employee (whose identification has not been revealed in the indictment filed in a federal court in Manhattan) and was given the task of hiring a hitman for carrying out the assassination which was foiled by the authorities in the US authorities.

While wrapping up his high-profile visit to India, the White House stated that Finer "acknowledged" the establishment of a committee of enquiry by India for investigating the "lethal plotting" and emphasised the need for holding the people responsible accountable.

"Finer acknowledged India's establishment of a committee of enquiry to investigate lethal plotting in the United States and the importance of holding accountable anyone found responsible," said the White House in a readout while speaking about his meetings in the national capital.

India calls indictment a “matter of concern”

India's Ministry of External Affairs, reacting to the indictment filed by the Justice Department, called it a "matter of concern" and said that it is contrary to government policy.

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"We cannot share any further information on such security matters. As regards the case against an individual that has been filed in a US court allegedly linking him to an Indian official, this is a matter of concern. We have said and let me reiterate that this is contrary to government policy,” said Arindam Bagchi, MEA spokesperson.

"The nexus between organised crime, trafficking and gun running and extremists at an international level is a serious issue for law enforcement agencies and organisations to consider and it is precisely for that reason that a high-level committee has been constituted and we will, obviously, be guided by its results," the spokesperson said.

• KAJAL AGARWAL