All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
If all the people of this country are Muslims, then in principle the meat of animals slaughtered there is lawful unless the contrary is proven. ‘Aa’ishah narrated that people asked the Prophet : "O Prophet of Allaah, meat is brought to us by some people and we do not know whether or not they mentioned the Name of Allaah on it (when slaughtering the animal). Then the Prophet said: ''Mention the Name of Allaah on it and eat from it.” [Al-Bukhari] Therefore, in this case the doubt should not be taken into account.
However, if there are Muslims and non-Muslims in the country, then in principle the animals slaughtered there are not lawful. Nevertheless, if most of the people of the country are Muslims, then the meat is considered to be lawful acting according to the majority which implies that it is more likely that their meat is lawful and this is given priority over the principle which implies its unlawfulness, as stated by As-Suyooti in his book “Al-Ashbaah Wan-Nathaa’ir” quoting Abu Is-Haaq Al-Isfraayeeni .
Allaah Knows best.