XI'AN - Doctors in a Northwest China city are closely monitoring an 18-month-old girl who is repeatedly expelling nails even though, the hospital claimed, there is no evidence that she had previously swallowed them.

Doctors at the Children's Hospital of Yulin city, Shaanxi province, where the bizarre case is being investigated, said the baby girl has excreted 21 nails and a steel pin during the past month, though she has not show signs of uneasiness and eats and drinks as usual.

"At first we thought the baby accidentally swallowed such things, but after being confined in the hospital she continued to expel nails day by day. And more surprisingly, X-rays showed new nails in her stomach after each excretion," He Bo, president of the hospital said.

He said babies might consume irregular objects such as charcoal or glass in rare cases due to the lack of certain minerals in their bodies, but this case they are monitoring has no precedent.

The baby's parents told reporters that they did not know how many nails are in their daughter's stomach. They even had the bizarre thought that their daughter might be "producing" nails in her stomach.

The doctors showed reporters four nails and a steel pin they claimed the girl has excreted.

It remains unknown if the baby girl consumed irregular objects during her hospital stay.

He Bo said, beginning now the girl will be placed under closer observation and would not be allowed to leave her hospital bed.