Washington: Amid the indictment of an Indian in an alleged foiled assassination plot in the US, State Department spokesperson Mathew Miller said on Tuesday that the US takes the matter 'very seriously', adding that India has launched its investigation into the matter and they will wait for the results.

"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," Miller said 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 added.

His statement comes after the US Justice Department unsealed an indictment against an Indian national for his alleged involvement in a foiled plot to assassinate a US-based leader of the Sikh Separatist Movement and a citizen in New York.

The Justice Department claimed that an Indian government employee (named CC-1), who was not identified in the indictment filed in a federal court in Manhattan, recruited an Indian national named Nikhil Gupta to hire a hitman to carry out the assassination, which was foiled by US authorities, according to prosecutors.

Gupta is currently in custody and has been charged with murder-for-hire, which carries a maximum sentence of 10 years in prison. Czech authorities arrested and detained Gupta on June 30, pursuant to the bilateral extradition treaty between the United States and the Czech Republic.

In its indictment, the Justice Department has claimed that earlier this year, an Indian government employee working together with others, including Gupta, directed a plot to assassinate a political activist who is a US citizen of Indian origin residing in New York City.

It was alleged that Gupta is an associate of CC-1 and described his involvement in international narcotics and weapons trafficking in his communications with CC-1. The indictment claims that CC -1 directed the assassination plot from India.

At CC-1's direction, Gupta allegedly contacted an individual whom he believed to be a criminal associate, but who was, in fact, a confidential source working with the DEA. The source, it was alleged, introduced Gupta to a purported hitman, who was a DEA undercover officer. The purported hitman was offered USD 100,000 to murder the Separatist leader, the Justice Department claimed.

The charges contained in the indictment are merely accusations, and the defendant is presumed innocent unless and until proven guilty, the Justice Department stated in a release.

The unsealing of the indictment follows the recent sharing of information by the US on a 'nexus' between organised criminals, gun runners and terrorists. India has since formed a high-level inquiry committee to address the security concerns highlighted by the US government.

Reacting to the Justice Department's indictment, the Ministry of External Affairs on Thursday said the case filed against an individual in a US court, allegedly linking him to an Indian official, was a "matter of concern" and is contrary to government policy.

"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" the MEA spokesperson said.

"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 added.