Sacks of crystal meth scooped from the sea by Burmese fishermen who mistook it for a deodorant substance had a street value of $20 million (£15.4m), an official said on Sunday, in a country believed to be the world's largest methamphetamine producer.

The accidental drug haul off Burma's coastal Ayeyarwady region occurred when fishermen spotted a total of 23 sacks floating in the Andaman Sea on Wednesday.

Each one contained plastic-wrapped bags labelled as Chinese green tea - packaging commonly used by Southeast Asian crime gangs to smuggle crystal meth to far-flung destinations including Japan, South Korea and Australia.

Locals were mystified by the crystallised substance in the sacks, Zaw Win, a local official of the National League for Democracy party who assisted the fishermen and police, told AFP.

At first, they assumed it was a natural deodorant chemical known as potassium alum, which is widely used in Burma.

"So they burned it, and some of them almost fainted," he said.

They informed the police, who on Thursday combed a beach and found an additional two sacks of the same substance - bringing the total to 691 kilogrammes (1,500 pounds) which would be worth about $20.2 million (£15.6m), Zaw Win said.

"In my entire life and my parents' lifetime, we have never seen drugs floating in the ocean before," he said.