Cardiff and Scarlets try to return dwelling from South Africa after the nation was placed on the UK crimson journey listing.
That might imply two United Rugby Championship (URC) matches for all sides being referred to as off.
UK Well being Secretary Sajid Javid mentioned from 12:00 GMT on Friday, six international locations can be added to the crimson listing.
Any British resident arriving from the international locations after 04:00 GMT on Sunday should quarantine in a resort.
These returning earlier than that may be requested to isolate at dwelling for 10 days.
Namibia, Zimbabwe, Botswana, Lesotho and Eswatini are the opposite African international locations are on the crimson listing.
The Welsh authorities has adopted journey guidelines for England in current occasions and any direct flight into the UK from South Africa would normally land in England.
The groups are exploring making an attempt to return dwelling on Friday earlier than the quarantine deadline with constitution flights being thought-about.
Scarlets chairman Simon Muderack mentioned on social media: “Many may have seen the information concerning the new Covid variant that impacts our folks in South Africa.
“We’re centered on the welfare of our workers in South Africa and the priority of their households at dwelling. We’re exploring all choices to repatriate our folks asap.”
Cardiff and Scarlets had been every as a result of play two video games in South Africa. They had been then scheduled to return to the UK for the Heineken Champions Cup marketing campaign, which begins on 10 December.
Irish aspect Munster and Italian staff Zebre are additionally presently in South Africa with all of the groups taking part in within the URC.
Cardiff and Scarlets had been meant to be the primary Welsh groups to play in South Africa within the competitors, which was launched for this season.
Scarlets had been scheduled to play Sharks in Durban on Saturday, 27 November and Cardiff going through Lions in Johannesburg the following day.
Each Welsh sides had been then to stay in South Africa, with Scarlets scheduled to face Bulls on Friday, 3 December at Loftus Versfeld, Pretoria, whereas Cardiff had been due in Cape City to face Stormers the next night.
These video games is not going to now go forward, however the Heineken Champions Cup motion on 11 December for Cardiff and Scarlets in opposition to Toulouse and Bristol respectively is likely to be performed if the squads can return earlier than the quarantine deadline.
These European fixtures would nonetheless be within the steadiness if the Cardiff and Scarlets gamers must quarantine at dwelling for 10 days on their arrival within the UK.
The preliminary URC plan was to ask South African sides to return to Europe in November and December, however that was scrapped.
In October, competitors bosses confirmed that spherical six and 7 fixtures for Sharks, Stormers, Lions and Bulls would happen on their dwelling soil.
The choice was taken as a result of South Africa had been taken off the UK authorities’s journey crimson listing, eradicating the necessity for quarantine on return.