Seasonal rains are set to disrupt nickel mining in the Philippines for the next four months or so, crimping exports to top buyer China and stoking a shortfall in the global supply of ore.

Miners in the Philippines say they will be able to fulfil their 2014 contracts as they have factored in the impact of the annual monsoon.

But, with a ban on raw metal shipments by former top exporter Indonesia, the seasonal decline in the Philippines' output could force China's vast stainless steel industry to run down its stocksof nickel ore, reigniting a rally in nickel prices.

Most producers in the Philippines' main nickel mining region of Caraga are expected to close operations as normal from October or November until early next year in anticipation of heavy rains.

The Philippines has emerged as the top supplier to China's producers of nickel pig iron, a key ingredient in stainless steel.

"They (China NPI makers) are definitely going to be caught short," said Daniel Hynes, analyst at ANZ in Sydney.

"Obviously they'll just have to dig into their inventory to meet demand in the shorter term or look at importing some ferronickel from various sources."

Nickel laterite ore is found mostly in Indonesia, the Philippines and New Caledonia, and has been increasingly manufactured into NPI by stainless steel mills as a cut price alternative to refined nickel.

Those firms have blended lower grade ore from the Philippines with their remaining Indonesian stocks to stretch them out, although analysts say stockpiles may be depleted early next year.

Expectations that China's stainless steel mills would run out of ore after Indonesia's ban helped benchmark nickel prices surge more than 50 percent by May. They have since cut gains to around 20 percent for the year, standing at around $16,550 a tonne.

"The Philippines has been exporting record volumes of nickel ore," said Ivan Szpakowski, a Hong Kong-based commodities strategist for Citi.

"Now you're entering the monsoon season, exports should be falling off dramatically in the following weeks. Nickel pig iron producers will be running through these inventories."

China's imports of nickel ore from the Philippines jumped 26 percent from January to August.

"If producers decide to hoard the inventories, you could see nickel prices spike before the end of the year," Szpakowski added.

Citi expects nickel to outperform prices for other metals, hitting $26,000 a tonne in 12 months.

HEAVY RAIN

Mines in the Philippines' southern Caraga region are bracing for heavy rains in the next four months, the country's Mines and Geosciences Bureau (MGB) said, including three operated by top producer and exporter Nickel Asia Corp.

MGB data shows there are at least a dozen nickel mines in Caraga, and 10 of them had no output in the first quarter of this year. The country has a total of 27 nickel mines.

Miners stressed that they had factored in the rainy season when setting production targets earlier in the year.

"Our mines in Surigao (in Caraga) adjust their schedules for the rainy season and make sure they've met their targets before the rains ... require them to go into maintenance mode," said Nickel Asia Spokesman Jose Bayani Baylon.

Nickel Asia expects to ship 17 million wet metric tonnes (WMT) this year, up 21 percent from last year. The company on Monday said its four operating mines sold a total of 14.26 million WMT in January to September, up 38 percent from a year earlier.

Unlisted Carrascal Nickel Corp, another Philippine ore supplier, confirmed it would halt production from this month and resume operations by March next year.