Turkey is staying away from Europe’s largest human rights conference for a second straight year because it wasn’t allowed to prevent the participation of non-governmental organizations that it finds objectionable, AP reported.

The Helsinki Commission, a U.S. government agency, tweeted Monday that “Turkey is the only country boycotting ... because it insists on having the ability to veto NGOs wishing to participate.”

The yearly two-week conference, which opened Monday in Warsaw, is devoted to democracy and human rights. It is organized by the Organization for Security and Cooperation in Europe, which comprises 57 states from North America, Europe and Central Asia.

The conference is unique because it allows civil society groups, no matter how small, to participate on an equal footing with governments. With many of the participants from countries with authoritarian governments in the former Soviet space, it is sometimes the only chance some democracy activists have to address government representatives from their own countries.

The Turkish delegation staged a walkout of the meeting last year after failing to block groups affiliated with cleric Fethullah Gulen, whom Turkish President Recep Tayyip Erdogan blames for a failed 2016 coup. This year, no Turkish delegation showed up at all, its seat empty.