BANGKOK (REUTERS) - Rubber farmers in Thailand, one of the world's biggest exporters of natural rubber, threatened on Friday (Nov 10) to protest in the capital Bangkok if the military government does not help to prop up falling prices of the commodity.

Prices of Thai natural rubber have fallen from a peak of 179.25 baht (S$7.36) per kg in 2011 to 47.75 baht on Friday. But Thai authorities said prices have similarly slumped in other major producers of the commodity.

Protests are rare in the junta-ruled South-east Asian country where a ban on public gatherings has been in place since a 2014 coup.

The Natural Rubber Council of Thailand said farmers in the rubber-growing south were calling on the authorities for help.

"The price of rubber is now lower than the cost of production," Uthai Sonlucksub, president of the council, told Reuters.

Some farmers from the south want to protest on Monday and accuse the Rubber Authority of Thailand, a government agency, of mismanagement, Mr Uthai said. He did not give details on the kind of help the farmers want.

Thailand, along with Indonesia and Malaysia, produce nearly 70 per cent of the world's natural rubber. The three countries agreed last year to cut exports to boost market prices but their targets have not always been met.

The Thai rubber authority denied the accusations of mismanagement.

"Rubber prices are currently low in all of the major rubber-producing countries. We are doing our best," said Sunan Nuanphromsakul, the authority's deputy governor.

Thailand's rubber farmers are politically powerful. In 2013, hundreds of farmers staged protests around the country, blocking roads and a regional airport in the south.

Those demonstrations eventually turned into a bigger political movement that led to the ouster in 2014 of a civilian government led by then-Prime Minister Yingluck Shinawatra.

Thai benchmark unsmoked rubber sheet was quoted at 43.60 baht per kg on Thursday, less than half of this year's peak reached in January.