Israeli cybersecurity company NSO Group, which is at the centre of the Pegasus snooping scandal, has temporarily blocked several government clients around the world from using its spyware technology as the firm probes its alleged abuses, according to a US media report.

The alleged use of the Pegasus software to spy on journalists, human rights defenders, politicians and others in a number of countries, including India, triggered concerns over issues relating to privacy.

The suspensions are in response to an investigation by the Pegasus Project, a consortium of media outlets that reported the company's Pegasus spyware was linked to hacks and potential surveillance.

"There is an investigation into some clients. Some of those clients have been temporarily suspended," National Public Radio (NPR) quoted a source in the Israeli company as saying.

The source, a company employee, did not name or quantify the government agencies or their countries that NSO has recently suspended from using its spyware, asserting that Israeli defence regulations prohibit the company from identifying its clients, the report by NPR, an independent, nonprofit media organisation, said.

NSO's ongoing internal investigation checked some of the telephone numbers of people that NSO's clients reportedly marked as potential targets.

"Almost everything we checked, we found no connection to Pegasus," the employee said, declining to elaborate on potential misuse NSO may have uncovered.

NSO "will no longer be responding to media inquiries on this matter and it will not play along with the vicious and slanderous campaign," the employee, who spoke on condition of anonymity because of company policy, said.

The Israeli government has also faced pressure since it regulates the sale of spyware technology to other countries. It has launched a probe into allegations against NSO.

Israeli officials inspected NSO's office in Herzliya, near Tel Aviv, on Wednesday "to assess the allegations raised in regards to the company," the defence ministry said in a statement.

The NSO employee said the company was cooperating fully with the probe and sought to prove to Israeli officials that the people named in the media reports were not Pegasus targets.

Mercury Public Affairs, which represents NSO Group, on Thursday said in a statement: "The company is working in full transparency with the Israeli authorities. We are confident that this inspection will prove the facts are as declared repeatedly by the Company against the false allegations made against us in the recent media attacks."

NSO says it has 60 customers in 40 countries, all of them intelligence agencies, law enforcement bodies and militaries, the reports said.

It says in recent years, before the media reports, it blocked its software from five governmental agencies, including two in the past year, after finding evidence of misuse.

The Washington Post reported the clients suspended include Saudi Arabia, Dubai in the United Arab Emirates and some public agencies in Mexico.

The company says it only sells its spyware to countries for the purpose of fighting terrorism and crime.

Nearly three weeks before Pegasus Project stories were published, NSO released its first report outlining its policies on combating the misuse of its technology and protecting human rights.

It cites a new procedure adopted last year to investigate allegations of potential software misuse.

Shmuel Sunray, who serves as general counsel to NSO Group, said the intense scrutiny facing the company was unfair considering its own vetting efforts.

"What we are doing is, what I think today is, the best standard that can be done," Sunray told NPR.

"We're on the one hand, I think, the world leaders in our human rights compliance, and on the other hand we're the poster child of human rights abuse."