Concerns over the Omicron coronavirus variant and fresh travel restrictions have led to a spike in hotel booking cancellations globally, online hotel search firm Trivago said on Tuesday, threatening to upend a fragile recovery in global tourism.

Cancellation rates increased to 35 per cent since November and holiday travel planning was down 10 per cent, the company said, adding that most travelers were choosing domestic destinations.

The company did not say what the cancellation rates were prior to November.

The Omicron outbreak, first reported in southern Africa, has led to a flurry of new testing rules and border closings, raising concerns ahead of the important Christmas travel season.

Multiple events ranging from sports and trade shows to corporate parties have been canceled, also leading to a slowdown in hotel bookings.

Private Label Manufacturing Association has canceled its annual trade show, which was scheduled to take place in Chicago in February next year, due to uncertainty sparked by the new variant.

U.S. investment bank Jefferies on Wednesday canceled client parties and virtually all but essential travel after nearly 40 new COVID-19 cases were reported at the firm.

Trivago said overall activity around holiday travel planning has slowed, growing by just 4 per cent since the variant was discovered. By comparison, Christmas travel increased by 34.7 per cent in the same one-to-two-week period in 2019.

Last month, the company said it saw an increase of 35 per cent in search traffic in the week leading up to Thanksgiving.

U.S. travelers are sticking with Las Vegas and New York as top holiday destinations, the company said.

"Much like 2020, domestic travel is the preferred option as consumers look to reunite with friends and family," Trivago said.

Last month, rival Booking Holdings Inc's travel website Kayak said international travel searches fell 5 per cent in the United States compared with a 26 per cent fall in Britain.

Fears over the variant have grown after British Prime Minister Boris Johnson warned of a "tidal wave" of new cases, with the country reporting the first publicly confirmed death in the world due to Omicron on Monday.

(Reporting by Aishwarya Nair and Amruta Khandekar in Bengaluru; Editing by Vinay Dwivedi, Sweta Singh Saumyadeb Chakrabarty)