Visitors to the Chengdu Research Base of Giant Panda Breeding will have to book tickets online during National Day holidays, according to a circular issued by the base Sunday.

Tickets will not be sold at the ticket office or ticket-selling machines at the base from Oct 1-7, National Day holidays.

As many as 60,000 tickets will be sold online for a single day over the period, 36,000 tickets for the morning and 24,000 for the afternoon, according to the notice.

The maximum number of visitors allowed together in the base will be 22,000.

If this number is reached, the base will stop admitting visitors and will operate on a one-out, one-in basis, the circular said.

The move aimed at preventing the base from overcrowding, which has been commonplace during previous holidays.

"On one peak day, as many as 100,000 visitors stayed in the base and they could not see pandas clearly at all.

They joked bitterly that pandas saw visitors instead of visitors seeing pandas," a base employee said.

Pandas are indigenous to China where they are scattered across Sichuan, Sha'anxi and Gansu provinces.

China had 548 captive pandas at the end of last year, 196 of whom were in the Chengdu base.