LONDON/AMSTERDAM (Reuters) -- The new Omicron coronavirus variant kept spreading around the world on Sunday, with 13 cases found in the Netherlands and two each in Denmark and Australia, even as more countries tried to seal themselves off by imposing travel restrictions.
Dutch health authorities announced that the 13 cases of the variant were found among passengers who were on flights from South Africa that arrived in Amsterdam on Friday.
“It is not unlikely more cases will appear in the Netherlands,” Health Minister Hugo de Jonge told a news conference in Rotterdam. “This could possibly be the tip of the iceberg.”
First discovered in South Africa, the variant has now been detected in Britain, Germany, Italy, the Netherlands, Denmark, Belgium, Botswana, Australia and Hong Kong.
The discovery of Omicron, dubbed a “variant of concern” last week by the World Health Organization, has sparked worries around the world that it could resist vaccinations and prolong the nearly two-year COVID-19 pandemic.
Omicron is potentially more contagious here than previous variants, although experts do not know yet if it will cause more or less severe COVID-19 compared to other strains.
Austria was investigating a suspected case on Sunday and in France Health Minister Olivier Veran said the variant was probably already circulating there.
Countries have imposed a wave of travel bans or curbs on southern Africa to try to stem the spread. Financial markets dived on Friday as investors worried that the variant could stall a global recovery. Oil prices tumbled by about $10 a barrel.
On Sunday, most Persian Gulf stock markets fell sharply in early trade, with the Saudi index suffering its biggest single-day fall in nearly two years.
Many countries have imposed or are planning restrictions on travel from southern Africa. The South African government denounced this on Saturday as unfair and potentially harmful to its economy - saying it is
 being punished for its scientific ability to identify coronavirus variants early.
In Britain, where two linked cases of Omicron identified on Saturday were connected to travel to southern Africa, the government announced measures to try to contain the spread, including stricter testing rules for people arriving in the country and requiring mask wearing in some settings.
The German state of Bavaria also announced two confirmed cases of the variant on Saturday. In Italy, the National Health Institute said a case of the new variant had been detected in Milan in a person coming from Mozambique.
Although epidemiologists say travel curbs may be too late to stop Omicron from circulating, many countries - including the United States, Brazil, Canada, European Union nations, Australia, Japan, South Korea and Thailand - have announced travel bans or restrictions on southern Africa.
More countries imposed such curbs on Sunday, including Indonesia and Saudi Arabia.
Omicron has emerged as many countries in Europe are already battling a surge in COVID-19 infec