At the time of independence in 1963 the Muslim population of Sabah was at 37%. Recent official statistics by the government of Malaysia puts Sabah's Muslim population at 63.7% .
In the early 1970s during the outbreak of the Moro rebellion in the southern Phillippines, thousands of Muslim refugees came to Sabah and settled in refugee camps. Many of them later acquired Malaysian citizenships illegally. In the early 1980s, when Datuk Harris Salleh was the Chief Minister of Sabah, tens of thousands Indonesians and Filipinos (most of them Muslims) acquired Malaysian citizenship illegally as detailed in the books by Joshua Kong (EPIC of Sabah) and M.D Mutalib (IC Palsu & Lelaki Malaysia Terakhir).
Apart from this we must also not forget the large number of West Malaysian civil servants who work and live in Sabah, most of whom are Muslims. Population surveys usually includes the legalized illegals, the illegals and West Malaysians as well.

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