Expo organizers on Wednesday pledged to come down heavily on staff members who take advantage of their position to queue up outside pavilions before the opening hours.

"(We have) to be fair," Hong Hao, director of the Bureau of Shanghai World Expo Coordination, said at a press conference.

There have been frequent complaints that a number of employees in the Expo Garden who are allowed enter through the gates a few hours before ordinary visitors queue up outside certain popular pavilions.

"As many as a couple of thousand of registered workers were waiting in queue," Hong said.

Those found breaking the rule the first time will be issued a warning and repeat offenders will have their personal passes canceled, Hong said.

"We've talked to some of them already," Hong added. "Most of them said they would never do it again."

The Expo passport is the hottest souvenir in the Expo Garden, which allows visitors to collect commemorative stamps of the pavilions they entered.

However, it has caused a few problems such as supplement shortage and requests for stamps on more than one passport.

Certain pavilions have even cancelled the stamp service due to frequent conflicts.

Hong said that the supply of Expo passports will be increased, while the Expo organizers will provide inkpads to each pavilion and repair the broken seal as soon as possible.

Expo organizers have an agreement with each pavilion to provide stamp services as long as they can.

However, staff from the Norway Pavilion, which scrapped the stamp service early this month, claimed they hadn't received any further notification yet.

Crowds of people pushing to get in through the easy access entrance have also led to several conflicts.

Expo officials have urged the exhibitors to ensure that only people aged over 75 and the disabled with a valid certificate are allowed to walk through the path with one other person.

Meanwhile, some 17,000 extra benches, 3,000 sunshades and 190 temporary drink trolleys have been installed in the Expo Garden recently to beat the heat.

Besides, 45 extra buses and 130 tour mobility cars have also been added at the venue.