Nigeria, Jan. 14 -- Visa applications from Nigeria, Russia and at least 73 other countries have been suspended as the United States tightens immigration screening over concerns about welfare dependence.

The US Department of State has instructed embassies and consulates to pause visa processing for the affected countries from January 21, pending a sweeping review of screening and vetting procedures.

The directive, contained in an internal memo first reported by Fox News, applies across several visa categories and will remain in force indefinitely.

Under the order, consular officers are to refuse applications using existing provisions of US immigration law while the reassessment is ongoing.

The affected countries cut across Africa, the ...