Turkey’s President, Recep Tayyip Erdogan, insisted on Thursday that the massacre of Armenians at the hands of Ottoman Turks a century ago was not a “genocide”.

Speaking at an international peace summit, Erdogan dismissed Armenian claims of genocide in 1915 were baseless, adding that he was willing to open the Turkish military archives to prove this.

“The Armenian claims on the 1915 events, and especially the numbers put forward, are all baseless and groundless,” he said, according to the Turkish daily Today’s Zaman.

“I say, we’re ready to open our military archives. We have no fear, no worries on this subject. Our ancestors did not persecute,” declared Erdogan.

Historians estimate that up to 1.5 million Armenians were killed by Ottoman Turks, an event widely viewed by scholars as the first genocide of the 20th century. Turkey denies that the deaths constituted genocide.

The issue has made headlines in recent days, as the world marks the 100th anniversary of the massacre.

Pope Francis recently publicly recognized the genocide, causing Turkey to recall its ambassador from the Vatican and raising the ire of Erdogan, who warned the Pope not to repeat such a “mistake” again.

On Wednesday, parties in the Austrian parliament signed a declaration recognizing the massacre as genocide, and Turkey reacted by recalling its ambassador from Vienna.

Last Thursday the EU Parliament also voted to recognize the genocide, which prompted a clarification from Parliament President Martin Schulz, who told Turkish Prime Minister Ahmet Davutoglu that he “understands” Ankara’s negative reaction to the vote.

Meanwhile, President Barack Obama has chosen not to recognize the genocide, despite an election promise he made during his 2008 presidential campaign.