Tin shipments from Indonesia slumped the most in eighteen months in July, dropping more than expected to the lowest level since last August as new purity standards in the world’s largest exporter came into force.

Data from the Trade Ministry showed that shipments fell 42% to 6,465.95 tonnes from 11,111.38 tonnes in June. That’s the steepest drop since a 64% plunge in January 2012 and compared with sales of 8,298.47 tonnes in July 2012. Exports exceeded the 28% drop forecast in a survey published July 31.

Declining supplies may help extend a rally in the price of the metal from a near 1 year low in July. Sales in June jumped to the highest level since December 2011 before the new standards took effect July 1. The rules, which were not as severe as initially planned, raised the minimum tin content limit to 99.9% from 99.85%.

Mr MB Gunawan president director at smelter PT Stanindo Inti Perkasa said that “The drop in exports is more than people had expected. The smelters either ran out of stockpiles after releasing them in June or they just couldn’t meet the rule.”

Tin futures for delivery in three months fell 1.3% to USD 21,655 per tonne on the London Metal Exchange. The metal used in soldering and packaging, which touched USD 18,809 on July 5, has tumbled 7.5% this year.

Mr Sukrisno President Director of PT Timah said that “Exports may remain low in August as smelters curb sales because of low prices. Last month’s shipments were the lowest since the country sold 5,645.87 tons in August 2012.”

According to the ministry’s data, based on surveyors’ reports prior to shipments, Indonesia shipped tin to 14 countries in July with Singapore taking 55% of the total. Other destinations included Taiwan, Malaysia and Japan.