The Secretary General of the Organisation of Islamic Cooperation (OIC), currently visiting Thailand, condemned the deadly explosion in Istanbul Tuesday as "an act of terror".
Iyad Ameen Madani was commenting on a suicide bombing in Istanbul's Sultanahmet district that killed at least 10 people and wounding scores of others - most of them German tourists.
Mr Madani said the planners of the "senseless brutality" should be quickly found, tried and persecuted for their crimes.
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He also extended his condolences to the government and people of Turkey, and the families of the victims.
He said the OIC would support all efforts of the Turkish government in its efforts in fighting terrorism.
In a statement issued to the media during his three-day Bangkok visit, Mr Madani also reiterated OIC policy. He said the 57-nation group "vigorously denounces all acts of terrorism and violent extremism in all forms and manifestations".
"There is no justification for terrorism," he said in the statement.