Tokyo's Ueno Zoo has already been visited by more than 4 million people this fiscal year, thanks to the arrival of two giant pandas from China that haved helped it top the mark for the first time in 19 years, zoo officials said Wednesday.

"At the current pace, we expect 4.4 million people to have visited the zoo by the end of March," one official said, noting the tally broke 4.05 million at the end of last month.

Attendance has been sluggish since the April 2008 death of giant panda Ling Ling, the zoo's star attraction since 1992.

But last April, the zoo reintroduced pandas for the first time in three years by leasing male panda Ri Ri and female Shin Shin from China. Attendance immediately surged.

The officials said about 3,000 visitors lined up outside the zoo for the pandas' debut on April 1, the start of fiscal 2011, and that large numbers of families continued to visit throughout the year. Weekends are especially crowded, they added.

Attendance last topped 4 million in fiscal 1992 — the year Ling Ling arrived. Some 4.01 million people passed through the zoo's gates that year. Both Ri Ri and Shin Shin are 6 years old, equivalent to about 20 in human years, and the zoo has high expectations they will successfully mate.