South African President Cyril Ramaphosa says there will be an investigation into the "mysterious" arrival of a chartered plane carrying 153 Palestinians from Gaza into the country.
The group arrived at OR Tambo International Airport but were initially refused entry and were stuck in the plane for more than 10 hours as they "did not have the customary departure stamps in their passports", local authorities said.
Most were eventually allowed in after intervention from a local charity and because of the government's "empathy [and] compassion", Ramaphosa said.
The circumstances of their departure from Gaza and travel to South Africa remain unclear.
South Africa has maintained strong support for the Palestinian cause throughout the war between Hamas and Israel in Gaza.
Ramaphosa said the group "somehow mysteriously were put on a plane that passed by Nairobi" and flew to South Africa, reports the News24 site.
Israeli military body Cogat, which controls Gaza's crossings, said in a statement: "The residents left the Gaza Strip after Cogat received approval from a third country to receive them." It did not specify the country.
According to the Palestinian embassy in South Africa, the group left Israel's Ramon Airport and flew to the country via the Kenyan capital, Nairobi, "without any prior note or coordination".
A statement from the embassy said "an unregistered and misleading organization [had] exploited the tragic humanitarian conditions of our people in Gaza, deceived families, collected money from them, and facilitated their travel in an irregular and irresponsible manner".
The BBC has asked the Kenyan government for comment.
Of the 153, 23 managed to fly on to other destinations, leaving 130 who were admitted into the country, South African authorities say.
Ramaphosa, speaking during an event in Johannesburg, said he was informed of the unfolding crisis by the home affairs minister.
In response, the president said "we cannot turn them back", according to News24.
"Even though they do not have the necessary documents and papers, these are people from a strife-torn, a war-torn country."
The president also told reporters the South African government would carry out a "proper evaluation" of the matter and update the public on "what is happening and how this matter came to be where it is", according to public broadcaster SABC.