Inventory of imported rubber in China's bonded warehouses in Qingdao, East China's Shandong Province fell 3.4 percent over a two-week period as tire makers shifted to cheaper local stocks on worries about the economy, trade sources said Wednesday.

The dip in the closely watched numbers could mean more pressure for global rubber prices as tire makers - the biggest importers of rubber - check their overseas purchases.

Tire-grade prices have sunk to multi-year lows on worries about global economic growth and weakening demand from top rubber user China, which accounts for 35 percent of ­global consumption.

Rubber stocks at Qingdao, which make up the bulk of China's inventories, currently stand at 330,300 tons, down from 341,900 tons in early July but still above the usual level of 250,000 tons, the sources said.

Inventories in the ware­houses are not disclosed publicly, but analysts collect data on quantities from offices in Qingdao, where tire grades are a few US cents cheaper than those offered in Southeast Asia.

"The stocks are very high anyway, so they need to draw them down," said Lee Chen Hoay, investment analyst at Phillip Futures in Singapore.