The Israeli spyware business NSO Group informed European legislators on Tuesday that at least five EU nations have used its software, claiming that the company had canceled at least one contract with an EU member country due to misuse of its Pegasus monitoring software.

Speaking to the European Parliament's committee investigating the use of spyware in Europe, NSO Group's General Counsel Chaim Gelfand admitted that the business had "made mistakes", but claimed that it had also lost a significant amount of cash by allegedly terminating contracts after the abuse was discovered.

Gelfand told members of the PEGA committee that the group was attempting to "do the right thing," claiming that every country that purchases the software is given due diligence regarding the law in the country beforehand.

Gelfand said he would return with a more concrete number, noting that at least 5 nations are using the tool.

Following findings that the malware is prevalent in Europe and has been used against some of the bloc's most famous politicians, including Spain's Prime Minister Pedro Sánchez and political parties in Spain, Poland, and Hungary, EU parliamentarians initiated the investigation.

Read next: NSO's Pegasus complex structure hampers EU probe

The issue in Spain has prompted a government inquiry into the activities of the country's intelligence service, CNI, which Catalan political organizations accuse of spying on leaders of the region's independence movement.

Carles Puigdemont, a member of the investigation committee and a Catalan politician who was targeted with Pegasus spyware, said he backed a total ban on the corporation, citing a recent US decision to blacklist the firm because the organization admitted that it cannot monitor its usage.

Read more: US defense company in talks over buying NSO's Pegasus

In March, the European Parliament formulated a special committee to investigate breaches of law after Hungary and Poland reported illegal use of the program by their respective governments. 

The meeting was the culmination of MPs' efforts since March to investigate and limit the use of invasive malware. It was a heated discussion that threatened to devolve into outright hostility as Gelfand dodged probing inquiries.

NSO has attempted to quell the criticism by claiming it hopes to see an international body regulating spyware.

“There’s a lot to be done, that's why we’re calling for an international standard," said Gelfand.