The closure of Everest's northeast ridge came after China told tourist agencies in Tibet to cancel all tours until April and stopped issuing entrance permits for Tibet to foreigners.
Tensions in Tibet are running high ahead of the anniversary of the Dalai Lama's flight into exile on Mar 10. Many Tibetans have chosen not to celebrate Tibetan New Year, or Losar.
China's move to close off Tibet will ensure a news black-out in case of any repeat of the violence that broke out last March.
Reporters in Tibetan areas of the surrounding provinces have already spotted large squads of riot police.
The Dalai Lama told Tibetan exiles that China's 'strike-hard' campaign is now fully in force in Tibet.
Climbers, who prefer the southeastern route through Nepal that was taken by Sir Edmund Hillary, less travel the Tibetan side of Everest, or Mount Chomolungma in Tibetan.