Expo organizers are to stop selling standard-day and multi-day tickets from Wednesday to control visitor numbers over the event's final two months.

More than 520,000 visitors crowded the Expo site yesterday, making it the second busiest day since the Shanghai Expo opened on May 1. Last Saturday, more than 560,000 visitors poured into the park, a record high.

Among yesterday's visitors, more than 110,000 visitors had complimentary tickets issued by the Shanghai government.

The Ticketing Center of the Expo said yesterday that only intraday tickets (including night tickets available from 4pm) and peak-day tickets for the National Day holiday (October 1 to 7) and last week of the Expo (October 25 to 31) would be available from Wednesday.

The move is aimed at ensuring the smooth operation of the Expo over the last two months and make visitors more comfortable, said Zhao Lei, deputy director of the center.

Huge numbers of visitors are expected at the Expo site in the final months according to the experience of previous World Expos.

People tended to flock to the Expo in the last two months as closing time drew near and foreign pavilions began to offer discounts on their products, Chen Xianjin, deputy director general of the Expo bureau said.

Zhao said the organizers had reached its target on sales of standard-day tickets that cost 160 yuan (US$23.52) each, but declined to say what that number was.

She said many visitors with standard-day tickets had yet to visit the Expo and there were worries they might all come at the same time.

Sales of the three-day (400 yuan) and seven-day (900 yuan) tickets have stopped as they had all sold out.

Multi-day tickets have been popular since selling began in January because of their lower prices for each day compared to the standard-day ticket, officials said.

People can buy intraday tickets at the Expo entrances. Zhao said the supply would be sufficient.

Peak-day tickets will be available at 64 branches around China of four designated ticket sales agents: China Mobile, China Telecom, Bank of Communications and China Post.

Shanghai has six branches selling the peak-day tickets.

Visitors will also be allowed to buy the intraday tickets for the next day after 4pm every day from Wednesday.

Seniors, physically challenged people, students, children and military personnel will still be eligible for discounts.

By 9pm yesterday, more than 46.5 million people had visited the Expo.