The authorities closed Tibet in March over anniversaries of the Tibetan uprisings against the Chinese rule, saying the travel was suspended for the sake of travelers' safety.
In early March 2008, Tibet was plagued by unrest, which started when Buddhist monks took to the streets to mark the 49th anniversary of a failed uprising against Chinese rule. The unrest left 19 people dead and 623 injured, according to official Chinese reports.
Beijing accused the Nobel Peace Prize winner and Tibet's exiled spiritual leader, the Dalai Lama, of orchestrating the trouble. The Dalai Lama denied the allegations.
The Dalai Lama, who fled Tibet in 1959, has repeatedly said he seeks autonomy for Tibet rather than independence from China.
More than 500 foreign tourists traveling with over 200 groups are expected to visit Tibet before April 20, according to the Tibet regional tourism bureau, Xinhua said.