Manila: The head of the world's largest body of Muslim-majority countries has strongly condemned the twin bombings of a Catholic church in the Philippines that killed 20 people and wounded more than 80.

The general secretary of the 57-nation Organisation of Islamic Cooperation, Yousef al-Othaimeen has also expressed his "deep indignation" at Sunday's terrorist attack.

Police investigators examine the site after the bombings in Jolo, Philippines. Credit:AP

He says the OIC firmly rejected all forms of violence, extremism and terrorism, whatever their sources or motives.

Pope Francis also condemned the bombings.