Among the accounts reportedly breached was the personal account of the prime minister’s top aide Michal Dworczyk.

The email accounts of about a dozen members of parliament were hacked recently, Polish counter-intelligence said on Friday, disclosing further details of one of the biggest cyberattacks on the country in recent years.

The revelations come two weeks after the authorities said top Polish government officials had been hit by a far-reaching cyberattack conducted in June that affected over 100 email accounts of current and former government officials.

Among the accounts reportedly breached was the personal account of the prime minister’s top aide Michal Dworczyk, an intrusion that spurred a series of leaks that have led to opposition criticism of officials for using private accounts to exchange confidential documents.

In a statement on Friday, counter-intelligence authorities said members of parliament hit in the hacking come from almost every parliamentary opposition grouping, and those affected had been notified and had received cybersecurity training.

The statement did not identify the lawmakers hacked.

Polish counter-intelligence said on June 22 that evidence showed links between the hackers and Russia’s secret services.

It said the attack was carried out by hackers known as UNC1151, adding the group’s actions are part of a campaign known as Ghostwriter that has targeted Polish politicians in recent months and that has also affected other countries in the region.

The Russian government and the Kremlin have repeatedly denied carrying out or tolerating cyber attacks following allegations from the United States about cyber attacks on US territory, Ukraine and Saudi Arabia.

Poland’s lower house of parliament, the Sejm, was not immediately available for comment.