The closure comes ahead of new border changes set to come into place on January 1. If Brexit talks are successful, Gibraltar will then become part of the Schengen zone with border controls for UK arrivals for the first time.
ADVERTISEMENTGibraltar has become the latest country to ban arrivals from the UK after cases of a new variant of coronavirus were detected in the autonomous British territory.
Only certain travellers will be permitted entry to the Rock following news that new COVID-19 variant was spreading rapidly in south-east England and had already accounted for more than 62 per cent of COVID-19 infections in London.
The travel ban comes as the Spanish government closed the country's borders to arrivals from the UK except for Spanish nationals on Monday to prevent the further spread of cases on the Iberian peninsula.
Spain has also increased border controls on its land border with Gibraltar, where at least one case of the new COVID-19 variant has already been found, a spokesperson for UK prime minister Boris Johnson confirmed.
An average of 30,000 people crosses the border that separates the British enclave from southern Spain every day.
Preliminary analyses of the new variant carried out so far reveal an estimated potential to increase the reproduction rate by 0.4 or more and an increase in transmissibility of up to 70 per cent, the European Center for Disease Prevention and Control (ECDC) said on Monday.
Believed to be more transmissible than the original coronavirus, the discovery of the new variant led to more than 40 countries closing their borders to UK travellers on Sunday and Monday.
The travel ban comes as negotiations between Gibraltar, Spain and the UK continue to remove the land border between Spain and Gibraltar by January 1, a direct consequence of Brexit.
The territory has been a British colony for three centuries and remains a strategic stronghold for Britain with more than half the world's marine traffic passing through the Strait of Gibraltar.
However, more than 95 per cent of Gibraltarians, or Llanitos as they are popularly known, voted to remain in the European Union in the 2016 referendum.
If talks are successful, Gibraltar will for the first time become part of the Schengen zone which allows free movement through 26 European countries - 22 member states plus Switzerland, Norway, Norway, Iceland, and Liechtenstein.
Frontex, the EU's border agency, will take over the border in Gilbraltar to allow Spanish citizens and Llanitos to pass freely across the European frontier by land and from the colony's airport.
The move will mean, however, that there will be border controls for UK nationals travelling to the British territory for the first time.
Who patrols the border has been a sticking point in the ongoing Brexit negotiations, with Spain originally signalling that it wanted to police the border itself, a red line for Gibraltar's chief minister, Fabian Picardo.