BEIJING - Tibetan deputies to China's National People's Congress (NPC), the parliament, have called for more train services on the Qinghai-Tibet Railway to cater for the increasing number of visitors to the plateau.

Ticket shortages and stranded passengers in busy travel seasons have created a "bottleneck" for tourism development, according to a motion submitted to the 5th session of the 11th NPC by the delegation from Tibet autonomous region.

Delegates proposed that trains linking Lhasa and the cities of Chengdu, Guangzhou, Chongqing and Lanzhou should depart daily instead of running every other day as now.

Currently, trains travel between Lhasa and Beijing and Lhasa and Shanghai on a daily basis, and daily between Lhasa and Xining only during busy seasons on the world's highest railway.

More ticket offices should be established in other Tibetan cities to ensure tourists get easy access to tickets, according to the motion.

The region has seen tourism boom since the 1,956-km railway began operations in July 2006. More than 8.6 million trips were made by visitors from home and abroad to Tibet last year.

Tibet is planning to attract 15 million visitors annually by 2015, with annual tourist revenue expected to hit 15 billion yuan ($2.38 billion) in the 2011-2015 period.