SARAJEVO (Daily Star)—Turkish authorities on Wednesday stopped Bosnian Serb leader Milorad Dodik’s airplane from flying over Turkish territory, preventing him from attending a ceremony to mark the centenary of the Armenian Genocide in Yerevan, Dodik’s office reports.

“Although all authorizations for this flight had been obtained, Turkish authorities did not allow the flight over their territory,” Dodik’s cabinet said in a statement to the Daily Star of Lebanon.

The plane carrying the president of Republika Srpska, a Serb-run entity of Bosnia, returned to his capital Banja Luka after spending four and a half hours at an airport in eastern Bulgaria, waiting in vain for authorization to fly over Turkish territory, the statement said.

Hundreds of thousands are expected to flock to genocide memorial in Armenia’s capital Yerevan on Friday to mark the start of a tragedy that still stirs deep divisions.

Ex-Soviet Armenia and the huge Armenian diaspora worldwide have battled for decades to get the World War I massacres at the hands of Ottoman forces between 1915 and 1918 recognized as a genocide. But Turkey rejects the term or any responsibility for crimes against humanity and has fought against the recognition of the Armenian Genocide.

French President Francois Hollande and his Russian counterpart Vladimir Putin are among those expected to attend Friday’s ceremonies.

Earlier this month Dodik submitted to the Republika Srpska’s parliament a declaration recognizing the Armenian Genocide.

The legislative body will likely adopt the declaration in the coming days.

But Bosnian Muslim political leaders, who view Turkey as their main international ally, have criticized the initiative.