Border restrictions were being tightened around the world on Monday in the face of the unrelenting coronavirus threat. Anger at social distancing rules erupted into violent clashes between police and protestors in the Netherlands. The United States is set to join France, Israel and Sweden in refusing arrivals from certain countries, as concern deepens about new strains of the Covid virus that originated in Britain and South Africa.Mexico's President Andres Manuel Lopez Obrador became the latest public figure to test positive for the disease. New Zealand reported its first case for more than two months.In Washington, President Joe Biden will on Monday reimpose a travel ban on most non-US citizens who have been in South Africa, Britain, Brazil, Ireland and much of the rest of Europe.Global death toll passes two millionCovid-19 has now killed more than 2.1 million people, with almost 99 million cases registered.On Sunday, France started demanding a negative PCR test for arrivals by sea and air from European Union neighbours.Sweden said it would prohibit entry from neighbouring Norway for three weeks, after cases of the more infectious British strain were detected in Oslo.And in Israel, Prime Minister Benjamin Netanyahu said the country was "closing the skies hermetically, except for rare exceptions" to both arrivals and departures for a week.Violent clashes in the NetherlandsProtests against a coronavirus curfew in the Netherlands degenerated into clashes with police and looting in cities across the country on Sunday, a day after a Covid-19 testing centre was set on fire in the northern village of Urk.Police used water cannon and dogs in Amsterdam, public television NOS reported, after hundreds gathered to protest the 9 pm-4:30 am curfew, set to remain in force until 10 February.At least 30 people were arrested in Eindhoven, where mayor John Jorritsma told reporters that, if the country continued "down this path, then I think we are heading for civil war".Virus 'aggravating inequality,' Oxfam warnsOn the long-term economic impacts of the pandemic, anti-poverty group Oxfam said Monday the emergency was aggravating inequality."The 1,000 richest people on the planet recouped their Covid-19 losses within just nine months, but it could take more than a decade for the world's poorest to recover," the group said.