Muenster, Germany  - Two pairs of tortoise twins in the space of a month have got a German zoo wondering what other amazing feats the animal kingdom will offer.

"We've found no record of Indian star tortoises even having twins," said an official of the Muenster Zoo on Monday. "Or at least, nobody has written it up."

All four infants were undersized, 6 to 8 grams, having had to share a normal-sized egg with a sibling.

Normal hatchlings weigh 16 grams. The animals, which grow to about 30 centimetres long, are popular in the pet trade. The zoo obtained the parents after Hong Kong customs officers confiscated them from smugglers.

One set of twins hatched June 13, and the other, from different parents, on July 10.(dpa)