I was born in Palestine of British parents during the British

I was born in Palestine of British parents during the British Mandate there in 1943. My birth was registered with the civil authority of the time. My birth certificate was lost along with my passport back in 1983. As I already had had a passport I didn't need a birth certificate to get a new one. Nor have I needed a birth certificate as my passport had been deemed good enough for identification purposes. I now want to emigrate to Canada where they insist they need to see my birth certificate. My birth is not registered her in the UK. According to the authorities here the repository of birth certificates etc in Palestine was burnt down in 1948 during the Arab/Israeli conflict. The Canadian authorities will accept a sworn affidavit. Who would have to swear and who do I go to to get one? Sorry for the rather convoluted story.