Pro-PKK Peoples' Democratic Party (HDP) Co-Chair Pervin Buldan acknowledged that the party has forged a secret alliance with the main opposition Republican People's Party (CHP) in the June 23 local elections, as she noted that their voter base was disturbed about the lack of transparency.

President Recep Tayyip Erdoğan had criticized the CHP and the Good Party (IP), which formed the Nation Alliance in the local elections for secretly including the HDP, but the parties had previously denied claims about the cooperation.

Buldan told a local news outlet that the HDP voter base is disturbed about cooperating with parties that are scared to openly declare their collaboration with the HDP.

"They consistently tell us that the alliance we formed in the June 23 elections should've been more transparent," Buldan said.

She confessed that the party had especially cooperated with the CHP and IP to make sure that the ruling Justice and Development Party (AK Party) did not win the polls in Istanbul.

"For the sake of winning the elections in Istanbul, and to explain how HDP's existence affects the outcome, we accepted the alliance offer for once," Buldan said, adding that her party will not accept such alliances from now on if the CHP and IP do not openly announce their cooperation.

The HDP announced previously that it would not nominate mayoral candidates in seven major municipalities, including Istanbul, İzmir and Ankara, in the municipal elections, which further proved claims that they were cooperating with the Nation Alliance.

The Turkish government has long accused the HDP of close links with the PKK. The HDP is known for its support of autonomy in regions where large Kurdish populations live. Also, some of its members have been charged or accused of having links to the terrorist organization. Its former co-leader, Selahattin Demirtaş, was arrested in November 2016 over terrorist propaganda.

The CHP has refrained from officially including the HDP in its electoral alliance, amid fears of a possible backlash from its secular-nationalist voter base. Yet, the candidate lists for the upcoming elections unveiled the scope of cooperation between the CHP and HDP, which led to some harsh reactions within its own party organization.