China is keeping foreign travelers out of Tibet during sensitive political anniversaries.

Travel agencies contacted Wednesday said foreign tourists would not be allowed into the Himalayan region until April 1.

It's not clear when the ban started, although some monitoring groups said it started this month.

March 10 is the 60th anniversary of an abortive 1959 uprising against Chinese rule in Tibet, while anti-government riots occurred March 14, 2008, in the regional capital Lhasa.

While the foreigner travel ban is an annual occurrence, the occasion of the 60th anniversary is drawing special attention from the authorities.

Amid heavy security on the ground, Tibet is almost entirely closed to foreign journalists and diplomats and information about actual conditions there is hard to obtain.