Foreign tourists are believed to have been banned from visiting Tibet after months of unrest.
Reports by international news agencies say the ban applies to all non-Chinese visitors and checks are being carried out in hotels.
Holidaymakers who have already booked trips have been advised to contact their tour operators.
Adventure tour operator Exodus Travels told the Daily Mail it was uncertain how long restrictions would be in place. The company has cancelled all trips to Tibet until the end of August and will be regularly reviewing departures in September and October.
The ban follows several public suicides in Tibet, including that of two youths who set themselves on fire in front of the Jokhang Temple in the centre of the old part of the capital, Lhasa, in May. Soon after, a mother of three killed herself outside the Jonang Dzamthang monastery.
More than 30 people have been known to set themselves alight in protest in the last year, said the Mail.
An FCO spokeswoman said: ‘We are aware of reports that Tibet has been closed to foreign visitors. Authorities periodically suspend issuing permits for travel to, and within, the Tibet Autonomous Region for foreign nationals at different periods during the year and for different reasons.
‘Travellers to Tibet should check with tour operators or travel agents and monitor the FCO’s travel advice for information about travel to Tibet."
All foreigners require visas to enter Tibet and they must join an official tour group.
By Linsey McNeill
