Donald Trump calls for 'extreme vetting' of immigrants to US


US Republican presidential nominee Donald Trump has said that he would enact "extreme vetting" of immigrants.


In a speech in Ohio, the candidate outlined his plans to combat Islamic extremism, including a new screening test for arrivals to the US.


Applicants will be tested to determine if they share Western liberal values, such as religious tolerance.


Citizens from some countries will not be issued visas but it is not clear which nations will be banned.