The Irish provinces could be left to play in a PRO14 Cup as reports from South Africa suggest the inaugural Rainbow Cup could be cancelled.
The new tournament is due to kick off the weekend after next, with Leinster v Munster and Connacht v Ulster pencilled in for the opening weekend, and with Irish, Welsh and South African sides playing each other until the fourth round.
The four big South African franchises were not due to travel to Europe until round four at the end of May.
However Sharks chief executive Eduard Coetzee said: "We have little information at this stage, but it seems to be the case that the Rainbow Cup will be cancelled."
According to reports in South Africa, plans to base the franchises in Bristol have been scuppered by the British government.
Basing themselves in Ireland seems like a non-starter too, given the Irish government's quarantine demands - anyone who travels from South Africa or who has been there in the last 14 days must spend 10 days in a hotel on arrival.
If the Rainbow Cup doesn't go ahead if will be a blow to the Springboks ahead of their summer Test series against the Lions.
Similarly, mandatory hotel quarantine regulations will come into place for anyone who travels from France to Ireland from next Thursday.
Fresh from their 45-0 opening Women's Six Nations victory in Cardiff yesterday, Ireland are scheduled to face France at Energia Park in Dublin next Saturday.
"We are in close contact with the IRFU who are addressing with the Irish authorities the latest travel restrictions," said a Six Nations spokesperson.
"We are exploring all possible options to play the Ireland versus France match."
An IRFU spokesperson said: "We're looking at all possible options."
Leinster will also learn later today which French side they are to face in the Champions Cup semi-finals on the weekend of April 30/May 1.
