Congress party supporters hold placards bearing images of Rahul Gandhi during a rally in March. Composite: Guardian/ AFP/Getty Images

Narendra Modi’s government has been accused of treason and “unforgivable sacrilege” by the political opposition in India following a series of reports by the Pegasus project revealing several journalists, activists and an opposition election strategist had their phone numbers included in a data leak of more than 50,000 numbers that, since 2016, are believed to have been selected as those of persons of interests by government clients of NSO Group.

The stories, published in the Guardian and in partner media outlets around the world on Sunday and Monday, revealed details of hundreds of verified Indian phone numbers that appear in leaked records of numbers.

They include two phone numbers belonging to India’s most prominent political opposition figure, Rahul Gandhi, who led the Congress party to defeat in the 2019 elections. The leaked records show his number was selected as a possible target the year before and in the months after the vote.

It is not possible to say whether a phone in the leaked data was infiltrated or successfully hacked without forensic analysis. But the investigation confirmed infections by NSO Group’s surveillance software Pegasus, or signs of potential targeting, on phones linked to 10 Indian numbers and on an additional 27 phones around the world.

The surveillance software, which India has never confirmed using, is licensed only to national governments. Analysis of the phone numbers selected for possible surveillance by the NSO client in question indicates that it was predominately used to target Indian numbers including those of critics of the Modi government.

In a statement, Congress accused the Modi government of being the “deployer and executor” of a “spying racket”.

“This is clearly treason and total abdication of national security by the Modi government, more so when the foreign company could possibly have access to this data,” said the Congress statement, which labelled Modi’s ruling Bharatiya Janata party (BJP) government as the “Bharatiya Jasoos [spy] party”.

“This is an unforgivable sacrilege and negation of constitutional oath by the home minister and the prime minister,” it added.

Traces of Pegasus – software with the ability to breach a phone, access its contents and turn it into a portable surveillance device – were found on the device of Prashant Kishor, an election strategist who clashed with Modi’s party during a state vote in April. Analysis of his phone showed he had been hacked using Pegasus as recently as the morning of the forensic examination.

Kishor told NDTV on Monday: “We used to suspect snooping but never realised hacking, that too from 2017 to 2021. Although I changed my handset five times, as the evidence suggests, hacking continues.”

Priyanka Gandhi, the general secretary of the Congress and sister to Rahul Gandhi, called the leaks “abhorrent” and an “affront to democracy”.

“If true, the Modi government seems to have launched a grave and sinister attack on the right to privacy – constitutionally guaranteed to Indian citizens as a Fundamental Right,” she said on Twitter.

The Pegasus project leaks prompted multiple denials from high-level figures in the Modi government, who sought to discredit the reports as coming from those with an “anti-India agenda”.

Speaking in parliament, India’s IT minister, Ashwini Vaishnaw – whose own phone numbers were identified as targets in 2017, before he entered parliament – said the project’s claims about Indian surveillance were an “attempt to malign Indian democracy and its well-established institutions”.

“In the past, similar claims were made regarding the use of Pegasus on WhatsApp. Those reports had no factual basis and were denied by all parties,” Vaishnaw said, to heckling from the opposition benches.

He added: “The presence of a number on the list does not amount to snooping … there is no factual basis to suggest that use of the data somehow amounts to surveillance”

NSO has always maintained it “does not operate the systems that it sells to vetted government customers, and does not have access to the data of its customers’ targets”, and has disputed that the data includes details of those its clients sought to target. In statements issued through its lawyers, NSO said it would “continue to investigate all credible claims of misuse and take appropriate action”.

Citing NSO’s denial, Vaishnaw said the list of countries published as using Pegasus was “incorrect” and that “any form of illegal surveillance was not possible” in India because of a rigorous process of bureaucratic checks and balances.

India’s home minister, Amit Shah, Modi’s closest political ally, accused “global organisations which do not like India to progress” of being behind the reports of possible surveillance of Indian politicians, journalists, activists and government critics.

“This is a report by the disrupters for the obstructers,” said Shah in a statement. “Disrupters are global organisations which do not like India to progress. Obstructers are political players in India who do not want India to progress. People of India are very good at understanding this chronology and connection.”

In a press conference, the former IT minister Ravi Shankar Prasad alleged that only India was being “targeted” for the use of Pegasus when 40 nations were using it, according to NSO. The Pegasus project is reporting on apparent abuse of the software by at least 10 countries.

Prasad accused Amnesty International, which had access to the leaked data, of having “an anti-India agenda”. He also accused the opposition Congress party of a role in the story because “they are losing power” and questioned whether the allegations were “some kind of revenge for the way India handled Covid?”

Many of those in India whose numbers appeared in the leaked data called for NSO to revoke the Indian government’s licence for Pegasus software due to “violations”. The software is only supposed to be used to investigate criminal activity or terrorism.

“Pegasus is a cyber-weapon, a controlled defence export from Israel under 2007 Act as per Wassenaar [Arrangement], with strict EUMA,” said Sushant Singh, an Indian journalist whose phone was examined by Amnesty’s Security Lab, the technical partner to the project.

It found proof that his phone had been compromised using Pegasus. “That [weapon] has been used in India against its own citizens,” he said. “Imagine if a fighter jet or missile of same category was used against Indians similarly. That’s it.”

This story first appeared on theguardian.com