"It's a plus factor to rice but not corn," Panganiban told a news conference.

La Nina features unusually cool surface temperatures in the Pacific Ocean resulting in storm surges and strong winds. The Philippine weather bureau has said typhoons, floods and rains since November may be linked to the development of the pattern.

The Philippines is one of the world's biggest buyers of rice, importing 1.8 million tonnes of the country's food staple last year after its own harvest was hit by the El Nino dry weather pattern in the first half.

The Philippines has so far placed orders to buy 749,500 tonnes of rice for delivery till May and has given a quota to private firms and local farmers' groups to bring in an additional 488,000 tonnes.

CORN THREAT

Panganiban warned that if no action was taken La Nina could damage corn crops.

"If nothing is done you lose about 300,000 tonnes," he said, adding flooding and incessant rains since December damaged newly planted corn in Cagayan Valley region in northern Philippines.

Grain traders in Manila said there were rumours that Philippine feedmillers plan next week to buy at least 25,000 tonnes of corn and 30,000 tonnes of Chinese wheat for animal feed for March shipment.

Officials at the Philippine Association of Feedmillers Inc. declined to confirm the reports, saying they were still assessing the impact of damage caused by La Nina in Cagayan Valley, the country's second largest corn growing area.

Traders said they expected the country's purchases of corn to rise to about 200,000 tonnes this year, nearly four times the 55,000 tonnes imported in 2005.

They said local feedmillers have so far placed orders for 160,000 tonnes of corn.

"Besides more import of corn, I also expect import of feedwheat to rise to 700,000-800,000 tonnes this year from around 600,000 tonnes last year," one grain trader said. Wheat is used as a substitute for corn for animal feed.

The same trader said he expected Philippine corn output this year to fall to 4.8 million tonnes from last year's 5.3 million due to La Nina.

The government has forecast corn production this year to rise to 5.5 million tonnes.

Panganiban said to minimise damage to corn production, the government would ask farmers in the southern region of Mindanao, a major corn-producing area, to grow more of the crop.

In the northern province of Cagayan Valley, where grain farmers are likely to be exposed to heavy rains, Panganiban said he would ask them to shift to planting rice.

But there is a risk the La Nina wet weather pattern could cause severe flooding, damaging the rice crop as well.