WARSAW, Poland (AP) — An attack Monday by unknown hackers idled the website of the Polish government office regulating public investment.

The Public Procurement Office said the attack came from outside servers Monday morning and only idled the office’s e-Procurements platform. The platform was still inaccessible in the afternoon. It was not immediately clear if there were any leaks.

Experts were working to restore its functioning.

The office’s task is to regulate public investment and ensures the hiring of companies is according to the law and transparent.

Poland’s government’s websites have been previously targeted by hacking attacks, believed to be mostly launched by Russian-speakers.

A break-in a few years ago into the private mailbox of a close aide to Prime Minister Mateusz Morawiecki has led to leaks on the Russian social media app Telegram, revealing informal email exchanges on some government decisions. Government officials have denied their authenticity.