Southern Kings announced on Tuesday that they would not play again for the rest of the year in any competition due to the financial impact of the coronavirus pandemic.
The club have faced crippling financial woes in recent months after a failed takeover bid, leading South Africa Rugby to assume control in June.
"Following several weeks of interrogation of the Kings' financial state of affairs we were left with a straightforward choice," Kings board chairman Andre Rademan said in a statement on Tuesday.
"We could opt to field the Kings in the domestic competitions mooted by SA Rugby for the sport's post-lockdown resumption if we so wished.
"If we did so, it would require additional loans to the Kings or extra investment from the shareholders to the tune of R6.5 million ($US385,591.91), which would add to the organisation's existing substantial debt.
"However, as there was no contractual requirement for the Kings to resume short-term participation in the PRO14 competition, because of air travel restrictions, and as the Kings had no other commercial commitments to honour, the most prudent decision was to withdraw."
A statement from the Pro14 confirmed that the Cheetahs also wouldn't compete due to the difficulties with cross border travel.
"Due to on-going travel restrictions enforced by the South African government against the backdrop of the COVID-19 pandemic, it is not foreseen that any cross-border Guinness PRO14 games involving South Africa teams will take place until 2021," it said.
"PRO14 Rugby remains in discussion with SA Rugby on when South African participation in the league can resume in the new year.
"Work is already underway to concentrate the opening 2020-21 fixtures among the 12 European-based clubs."
Both teams, who have competed in the Guinness PRO14 in Europe since 2017, were set to be one of eight teams competing in a domestic competition scheduled to start in September.
A consortium reached a deal to acquire 76% of the Kings in January 2019, which was billed as new dawn for the Port Elizabeth-based team, but it failed to come up with the necessary funds to complete the transaction.
Information from Reuters contributed to this report.