Giant panda cub Tai Shan (L) and his mother Mei Xiang play during the opening of the Giant Panda Habitat and Asia Trail at the National Zoo in Washington, in this Oct 17, 2006 file photo. Mei Xiang's newest cub, born Sept 16, 2012, died Sept 23, 2012, zoo officials reported.[Photo/Agencies]

WASHINGTON - A giant panda cub born at the US National Zoo in Washington a week ago has died, it was announced here on Sunday.

"We are brokenhearted to share that we have lost our little giant panda cub," said a statement from the zoo.

According to the statement, panda keepers and volunteers heard Mei Xiang, the cub's mother that had been nursing it since its birth on Sept 16, make a "distress vocalization at 9:17 am" Sunday, and alerted the veterinarian staff.

Zoo workers were able to safely retrieve the cub for an evaluation at 10:22 am, something the zoo said they only do "in situations of gravest concern," and performed CPR and other life- saving measures on it. But the cub was unresponsive.

The cause of death is unknown at this point, but the zoo said it will have more updates as experts learn more. It noted that the cub weighed just under 100 grams, and that there was no outward sign of trauma or infection.

Mei Xiang gave birth to her first cub, Tai Shan, in 2005. Tai Shan now lives in China. The National Zoo now houses Mei Xiang and Tian Tian, a pair of giant pandas on loan from China.