Turkey on Friday pledged to bring to justice those behind a bomb blast at the Ecumenical Orthodox patriarchate in Istanbul and said it had already stepped up protection of the building.

No one was hurt in the incident overnight Wednesday when a home-made bomb was lobbed over the wall around the patriarch’s residence and exploded in the garden, blowing out several windows and damaging the roof of a nearby cathedral.

“Security measures were immediately increased at and around the patriarchate and the police are continuing their investigation,” said a statement from Turkish Prime Minister Recep Tayyip Erdogan’s office.

“Our domestic security agencies are expending utmost effort to find those responsible for the attack, which we condemn violently, and bring them to justice,” the statement added.

The Turkish statement came after a call from neighbouring Greece for increased police protection of the patriarchate.

The ecumenical patriarchate in Istanbul is the Christian Orthodox world’s highest authority.

Last month about 1,000 Turkish ultra-nationalists demonstrated outside the patriarchate, burning an effigy of Patriarch Bartholomeus I, in protest at the patriarchate’s efforts to ensure the reopening of the only Greek Orthodox seminary in Turkey, closed since 1971.