The ruling party leader has denied that the government used the powerful software to hack its opponents.
The leader of Poland's ruling party has admitted that the country bought Pegasus spyware but has denied that it was used to target political opponents.
In an interview, Jaroslaw Kaczynski stated that security services in many countries have used the sofware to combat crime and corruption.
Poland's government has faced intense pressure this week to investigate claims that Pegasus was illegally used to hack opposition politicians.
The advanced spyware is owned by the Israeli surveillance software maker NSO Group -- who says pegasus can be used by authorities to fight criminal activity.
But an investigation in July found that Pegasus was used by European governments to hack journalists, activists, and politicians.
Once installed on a mobile phone, Pegasus can access a user's messages and data, or even activate the device remotely.
The Associated Press has reported that Krzysztof Brejza, a Polish senator from the main opposition Civic Platform (PO), was hacked using Pegasus in 2019.
Ahead of Poland's parliamentary elections, damaging messages from his phone were broadcast by state television in an apparent smear campaign.
Citizen Lab -- a Canadian-based cybersecurity monitoring lab -- has confirmed that the spyware was used against three people in Poland, including Brejza.
Amnesty International has also stated that the PO senator's phone was hacked multiple times in 2019.
Brejza has said that the incident allowed the ruling conservative Law and Justice (PiS) party to secure a narrow victory in the election.
But Kaczynski has dismissed the allegations and says the opposition "lost because they lost".
"There is nothing here, no fact, except the hysteria of the opposition," he told the weekly Sieci.
"No Pegasus, no service, no secretly obtained information of any kind played any role in the 2019 election campaign."
Brejza has since filed a slander complaint against Kaczynski while accusing the authorities of seeking political revenge.
The senator and his father, Ryszard Brejza, believe that PiS is still trying to cast suspicion on them as a way to justify the use of the surveillance software.
Kaczynski’s allies had previously denied that Poland purchased and used Pegasus, with Prime Minister Mateusz Morawiecki suggesting that a foreign intelligence service could have done the spying.
Kaczynski told Polish media that Pegasus could be used to combat the growing use of encryption to mask data in transit.
"It would be bad if the Polish services did not have this type of tool," Kaczynski said.
But the PiS leader stressed that any use of Pegasus was "always under the control of a court and the prosecutor's office".
But there have been repeated calls for an investigative commission in parliament to probe the matter. Opponents have labeled the scandal as the "Polish Watergate" -- referring to the resignation of former US President Richard Nixon in 1974.
John Scott-Railton, a senior researcher at Citizen Lab, also told AFP that the detected uses of Pegasus could just be "the tip of the iceberg".
The two other Polish targets identified by Citizen Lab were Roman Giertych, a lawyer who represents opposition politicians in a number of politically sensitive cases, and Ewa Wrzosek, an independent-minded prosecutor.