Nacewa and Jamison Gibson-Park, both New Zealanders were denied entry to South Africa because of a visa issue.
Club captain Isa Nacewa is one of two Leinster players denied entry to South Africa.
Both Isa Nacewa and Jamison Gibson-Park met problems when they arrived in the country and are now on their way to Ireland again with Nick McCarthy being called up to the touring squad.
'As this process is still ongoing, Leinster Rugby will be making no further statement'.
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.
Nacewa and Gibson-Park were refused entry on their arrival by customs at Tambo International Airport.
It is understood that the pair didn't have the necessary visa that New Zealanders require to enter the country. Leo Cullen's men are in South Africa to play the Southern Kings and the Toyota Cheetahs in the GUINNESS PRO14 over the next ten days.
In a statement released this afternoon, Leinster confirmed the process is ongoing.
History will be made this Saturday when South Africa hosts its first ever PRO14 matches as the Southern Kings entertain Leinster in Port Elizabeth (kick-off 2.15pm local time/1.15pm Irish time - live on SuperSport 1/TG4) before the Toyota Cheetahs host Zebre in Bloemfontein.