LONDON—Natural rubber buyers seemed unswayed by a proposal for new output curbs among the three main producer countries or efforts by supplier bodies to talk up the market, as prices continued to slide in Asian trading centers.

In recent weeks, the Association of Natural Rubber Producing Countries and the International Rubber Consortium forecast price recovery on the back of weather-related supply-disruptions and improved market sentiment, while Indonesia, Malaysia and Thailand have signaled a new plan to limit NR exports.

On the Shanghai Futures Exchange, the closing price for RU1709—the most heavily traded NR future—fell 12.8 percent since the start of April to close the trading week ended May 5 at $590 per mertic ton.

And Japan's TOCOM exchange saw back-month prices for reference RSS3 materials fall by 16.5 percent to $1.91 per kilogram between March 29 and April 26.

In Bangkok, prices for RSS1 and RSS3 grades dropped by 7.6 percent to $223.10 per 100 kilograms while RSS3 fell 7.7 percent to $219.75 per 100 kilograms between March 31 and May 5.

In Kuala Lumpur, prices for SMR-20 fell by 16.0 percent to $153.25 per 100 kilograms over the same trading period. Latex prices, meanwhile, slumped 18.9 percent to $144.40 also as of May 1.