TOKYO - Two giant pandas at Tokyo's Ueno Zoo mated for the first time in four years on Monday - a 52-second effort that boosted hopes for a baby as well as shares in a nearby Chinese restaurant.

Public viewing of pandas at the zoo has been halted since last week as the mating season got into full swing for the mammals, which are notoriously difficult to arouse.

But male Li Li and female Zhen Zhen, both 11 years old, eyed each other through a fence separating them, seeming to be in the mood for love, according to the zoo.

"We let the two be together at 8:06 am, and confirmed they mated for 52 seconds from 8:48 am," Ueno Zoo announced in a statement.

Four minutes later they were separated again.

"They usually live in solitude as pandas in the wild do," Ueno public relations official Hitoshi Suzuki told AFP on the phone.

"Living together could lead to quarrels and wounding each other."

Bloomberg said the mating coincided with a rise in the shares of Chinese restaurant chain Totenko - which has its main outlet within walking distance of the zoo - on hopes that a baby panda would draw tourists to the area.

The stock initially shot up nearly 10 percent but pared gains to close up 2.90 percent at 177 yen ($1.57) by the end of the day.

Totenko's shares have risen and fallen in line with panda news before according to Bloomberg. It said shares jumped as Shin Shin appeared to be expecting in 2013 - when the pandas last mated - but dove a month later on news the pregnancy was a false alarm.

Shin Shin, who was brought from China six years ago just before the massive earthquake and tsunami that devastated Japan's northeast, gave birth to a baby in 2012, the first at the zoo in 24 years.

But the cub died from pneumonia six days later.

Giant pandas are notoriously clumsy at mating, with males said to be bad at determining when a female is in the right frame of mind and often befuddled at knowing what to do next.

In the event the animals do feel compatible, sex is frequently over too quickly to impregnate the female, who is only receptive to the proposition for two or three days a year between February and May.