Egypt instituted a new policy requiring all Sudanese entering the country to obtain visas prior to entry, after detecting "unlawful activities" including the issuance of fraudulent visas, foreign ministry spokesman Ahmed Abu Zeid told Reuters.
The decision is a reversal of a longstanding exemption for children, women and elderly men.
More than 200,000 Sudanese have entered Egypt since fighting erupted in April, Abu Zeid said.