JAKARTA, Sept 26 (Reuters) - Indonesian refined tin shipments are expected drop by around 75 percent in September-December from the same period last year, the country's leading cargo surveyor said, after new trading rules slashed output in the world's top exporter.
The rules aimed at establishing a benchmark price in Indonesia have already driven the nation's biggest tin producer, state-backed PT Timah, to halt shipments and declare force majeure.
Analysts and traders are unsure how long it will take tin buyers and the country's 47 registered tin exporters to adjust, with the move helping push up international tin prices by 9 percent this month.
From September until year-end, Southeast Asia's largest economy will likely ship only 10,000 tonnes of tin, said the director of the minerals and coal division at PT Sucofindo, a state-owned company. That compares with around 38,000 tonnes in the same period in 2012.
"We estimate tin exports from September to December ... will be around 10,000 tonnes," said Sufrin Hannan.
"With the drop in tin exports we calculate that our revenue from the mineral and coal sector will also drop, because our revenue is volume sensitive," Hannan said, adding that only a few containers of tin had been exported so far this month.
Surveying mineral and coal cargoes is one of Sucofindo's top three sources of revenue.
Timah declared force majeure as customers had not registered to trade tin on the Indonesia Commodity and Derivatives Exchange (ICDX), the only approved exchange for physical tin trade. But the firm expects exports to improve in the next two months.
Other producers have also halted exports and lawmakers could face pressure to revamp the rules forcing producers to trade on the ICDX, with lower mineral sales hurting the rupiah currency - currently trading at its lowest in more than four years.
Benchmark London Metals Exchange tin prices were at around $23,200 a tonne on Thursday, slightly above ICDX prices at $22,830. (Reporting by Yayat Supriatna; Writing by Fergus Jensen; Editing by Joseph Radford)