WASHINGTON (REUTERS) - A rare giant panda born two weeks ago at the Smithsonian National Zoo is female, zoo officials announced on Thursday.

The cub appears to be in good health, with a round belly and loud cries, said Ms Jen Zoon, a zoo spokesman. The cub's gender was not immediately known after its birth on Aug 23, but tests by Smithsonian scientists proved it was female.

The cub, which has yet to be named, was born to 15-year-old panda Mei Xiang in the US national zoo and tests showed the father is 16-year-old Tian Tian of the same zoo.

"Mei Xiang is attentive when it cries, so she's being a very good mom," the spokesman said.

Giant pandas are one of the world's most endangered species and the cub was conceived through artificial insemination on March 30 with a mixture of fresh and frozen semen collected from Tian Tian and from Gao Gao, a resident of the San Diego Zoo.

Scientists also confirmed that a second, stillborn cub Mei Xiang delivered on Aug 24 was female and also was sired by Tian Tian. The cubs were fraternal twins, the zoo said.

The natural home of giant pandas is in a few mountain ranges in central China. There are about 1,600 known to be living in the wild and some 300 in captivity, mostly in China.

Female pandas are able to conceive only for two or three days in the spring. The gestation period is about five months.

Mei Xiang's first cub was born in 2005 and lives in China. A second cub died six days after birth last year.