Washington, Jan. 15 -- The US State Department is set to temporarily halt immigrant visa processing for applicants from 75 countries as it tightens enforcement of laws designed to prevent new arrivals from becoming dependent on public assistance, according to an internal memo seen by Fox News.

The pause, which is due to take effect on January 21, will apply while the department reviews and updates its screening and vetting standards.

Consular officers have been instructed to deny visas under existing legal authority during the review period, which has no specified end date, while any exemptions granted will be "very limited" and only after applicants clear so-called "public charge" considerations.

Countries reportedly affected include So...