Muslim scholars from around the world have gathered in the Hijri Calendar Union Congress in Istanbul on Saturday to agree on a unified and mutual Islamic calendar.

Muslim countries have been using different Hijri calendars for years that lead to confusion with varying religious holidays and different dates every year for key religious events such as Hajj, a once in a year event in which millions of Muslims gather for a pilgrimage.

The Hijri Calendar Congress, organized by Turkey's Presidency of Religious Affairs, the European Council for Fatwa and Research, Boğaziçi University's Kandilli Observatory and the Islamic Crescent Observation Project (ICOP), wants to solve this problem.

A single Hijri calendar project and a double calendar project will be presented to scholars, astronomers and decision makers from around 50 countries.

The opening speech of the congress was made by Mehmet Görmez, head of Turkey's Presidency of Religious Affairs. Görmez expressed his hope for mutual dates on religious festivals and celebrations throughout the world.

He said that the convention aims to mark the end of a 3-year-long collaborative work.

The congress started on May 28, Saturday and will end on May 30, Monday.