A series of travel restrictions were introduced by the Swiss Federal Council in response to the Omicron variant of COVID-19, which the World Health Organization said could pose a "very high" risk.

The Swiss Federal Council last week banned direct travel from Southern African countries, while passengers arriving from nations where the variant had appeared would be required to present a negative COVID-19 test and quarantine for 10 days.

The measure was introduced regardless of whether the individual had been vaccinated against COVID-19 or had recently recovered from the virus.

The travel restrictions led to the cancellation of the Lucerne 2021 Winter Universiade, which had been scheduled to run from December 11 to 21.

The Swiss Federal Council has since proposed an extending a requirement that COVID-19 certificates be presented at all events accessible to the public and to all amateur sports and cultural activities that take place indoors.

This would also see the abolishment of an exception for fixed groups of up to 30 people.

The certificate would also be required for outdoor events attended by 300 people, compared to the current threshold of 1,000.

Masks would be required in all places indoors where the COVID certificate is mandatory.

At sporting or cultural events which do not allow masks to be worn, it would become compulsory to collect the contact details of the people present.

Swiss Olympic claimed it supported the new measures, acknowledging that, while certificates being required for groups of 30 would impact training opportunities, it was acceptable as amateur sport could continue.

The organisation added it had already asked sports organisations to expand the mask mandate.

Swiss Olympic President Jürg Stahl has questioned the travel restrictions, with the organisation expressing concerns over the impact on the sport sector.

"Holding international sporting events in Switzerland is at risk, if not impossible, if the travel restrictions and quarantine regulations are upheld," Stahl said.

"This in turn puts athletes, organisers, associations and clubs (as well as various sectors of the economy) in great distress.

"As the umbrella organisation for Swiss sports, Swiss Olympic demands from the Federal Council and the cantons that a solution be found that enables the forthcoming international sporting events to be held and that top athletes are exempted from the quarantine regulations.

"Swiss Olympic is happy to help develop such a solution."

Several winter sport events appear at imminent risk due to travel restrictions.

Davos is due to host an International Ski Federation (FIS) Cross-Country World Cup on December 11 tand 12, while St Moritz is scheduled to take an FIS Alpine Ski World Cup event on the same dates.

A FIS Ski Cross World Cup is currently slated for December 13 to 15 in Arosa, while ski jumping competition is expected to take place at Engelberg from December 17 to 19.

Switzerland is also due to host several FIS competitions in January.

A neutral venue may have to be found for a UEFA Champions League group stage match between Manchester United and Young Boys, as the Swiss outfit may be forced to quarantine on return from the fixture in England next week.