Leinster duo Isa Nacewa and Jamison Gibson-Park have both been denied entry to South Africa ahead of their PRO14 fixture against the Southern Kings on Friday.
Nacewa, the Leinster captain, and scrum-half Gibson-Park ran into problems at O.R. Tambo airport after arriving in the country on Wednesday morning.
A new regulation was introduced by South African authorities in January this year, with the South African High Commission announcing the rule change last December.
"Effective on/after 16 January 2017, all diplomatic, official and ordinary passport holders of New Zealand will now require a visa to enter South Africa."
Friday's fixture is the first of two matches in the Republic for Leinster, who face the Cheetahs in Bloemfontein the following week.