An operation was launched by security forces after posters of jailed PKK leader Abdullah Öcalan as well as material for terrorist propaganda were found in the pro-PKK Peoples' Democratic Party’s (HDP) building in the Esenyurt district of Istanbul on Sunday.

Teams of the counterterrorism department of the police entered the HDP building after a search warrant was given by the chief public prosecutor’s office in Istanbul's Büyükçekmece district.

Following the investigation, posters and photos of Öcalan, 1,000 terrorist propaganda posters, magazines as well as books, DVDs, hard disks and laptops were found.

HDP Esenyurt heads Ercan S. and Dilan K. gave their testimonies at the police station for “making terrorist organization propaganda” and were released on conditions of trial without arrest.

“In none of the world’s democratic countries can this be allowed,” Interior Minister Süleyman Soylu tweeted on Sunday together with a video showing the inside of the HDP building and the terror propaganda material seized.

He stated that the abuse of democracy is always possible and criticized Western countries for demanding that Turkey tolerate terrorist acts while they themselves would not allow such incidents.

Öcalan, who founded the PKK in 1978, was arrested in 1999 due to his role in the terrorist group's decadeslong campaign against the Turkish state, which led to the deaths of more than 40,000 people.

The HDP has many times drawn ire for transferring taxpayer money and funds to the PKK, a globally recognized terrorist group. HDP mayors and local officials have been found to misuse funds in support of the PKK terrorist group and provide jobs to PKK sympathizers.

Speaking on the issue, Communications Director Fahrettin Altun tweeted on the same day: “Once again we see that HDP means PKK. What will those that form alliances with the HDP say in the face of this footage?”

Its mayors have also been accused of undermining municipal services, allowing the PKK to dig ditches in the streets and launch attacks on police and soldiers when the terrorist group adopted an urban warfare strategy in July 2015 and ended a two-year reconciliation period. HDP municipalities and their staff were also found to be actively participating in terrorist attacks launched after July 2015.

The party is also being accused of providing recruits to the terrorist organization by deceiving young people to join its ranks.

“Is there still anyone not understanding why the Diyarbakır families wait in front of HDP buildings?” Altun said, commenting on the video.

Several families have been participating in a demonstration in front of the HDP’s main headquarters in Diyarbakır for over a year, claiming that the party supports the PKK terrorists' recruiting and kidnapping of youth.

The Kurdish families' sit-in began as a reaction to the PKK, the terrorist group that recruited their children, and the HDP, a political party the families argue is allied with the terrorist organization.