Image caption The diamond's owner alerted the police after he saw the man consume the precious stone

A Chinese visitor to a gem exhibition in Sri Lanka has been arrested for swallowing a diamond said to be worth $13,000 (about £8,200), police say.

The 32-year-old man swallowed the gem after taking it from a display cabinet as the annual exhibition opened on Wednesday in the capital, Colombo.

"He... appeared to be appraising it and suddenly put it in his mouth," an unnamed police officer told AFP.

He said the man was taken to hospital to be given laxatives.

It is not yet clear whether the diamond has been recovered from the man, who was also arrested for attempted theft.

Police say that the suspect asked diamond owner Suresh de Silva for a close inspection of the gem.

Mr de Silva told the BBC's Charles Haviland in Colombo that he complained to police after seeing the visitor put the precious stone in his mouth and then swallow it.

He said that said the man, who had an accomplice, operated by swapping real gemstones with forged ones.

The stone which was swallowed might have been the false one and specialist tests will need to be conducted to ascertain which it is, Mr de Silva said.

Mr de Silva said the accomplice, who is also Chinese, had tried to distract him.

But the diamond owner saw the would-be thief brush his hand over his face and then panic, apparently after being spotted.

Mr de Silva said he had never known such a case before - swallowing a diamond was very risky, he said, because its point could damage the intestines.

Sri Lanka has a thriving gem industry but it does not mine diamonds. It is well known for its blue sapphires.