BBC NEWS | Middle East | Adult Siamese twins plead for separation

Doctors in Singapore are considering whether to separate a pair of 28-year-old twin sisters who are joined at the head - an unprecedented operation for adults.

The Iranian twins, Laleh and Ladan Bijani, have been undergoing intense physical and psychological tests since arriving in Singapore two weeks ago.

After God, we are relying on the team of doctors

Bijani sisters

Neurosurgeon Keith Goh says he and his team will decide by the end of the year if an operation can be successful.

The twins - who are both law graduates but have very different personalities - say they are optimistic they will one day lead separate lives.

They went to Singapore after hearing about the successful surgery led by Dr Goh on baby twins from Nepal who were also joined at the head.

The operation - if it goes ahead - involves separating two brains encased within a single bony structure in the head, Dr Goh said.

"The problem is that after 28 years of (the brains) lying in such close proximity and right next to each other, there will be connections that will have to be disconnected."

In 1996 German doctors refused to operate on the Bijani sisters after tests suggested that separating them could be fatal.

Sisters' anxiety

The twins say they want to be separated because of deep differences between them.

"We are two completely separate individuals who are stuck to each other," Ladan, the more extrovert of the sisters, told reporters.

"We have different lifestyles," she said. "We think very differently about issues."

The twins said that if their situation continues for much longer, they will not "stand it any more".

They say they feel no anxiety about the operation.

"We believe it's all in God's hands," Ladan said. "After God, we are relying on the team of doctors."

Siamese, or conjoined, twins occur in about one in every 100,000 births.

Their births can be extremely traumatic and approximately 40-60% are delivered stillborn with 35% surviving just one day.