Farmers in the Philippines will soon reap a harvest after using emergency seed supplies to grow crops following a devastating typhoon that struck during planting season, the UN food agency said Monday.

Super Typhoon Haiyan raked across the central Philippines last November, killing at least 6,200 people with around 2,000 others still missing, while also displacing four million and leaving tens of thousands of farmers without their livelihoods.

Haiyan hit at a "terrible time" between rice planting seasons but timely seed replacements have ensured a second harvest is not lost, said Jose Graziano da Silva, director-general of the Food and Agriculture Organisation (FAO).

Last year the agency had voiced concerns that without the harvest, vulnerable farmers would not have been able to collect rice for almost a year -- until October or November 2014.

"I am pleased to say that our support got there in time," he said in a speech to local farmers who received 1.76 million tonnes of seeds from the FAO after the typhoon.

"When the crop is harvested (in March or April)... it should yield enough rice to feed 800,000 people for more than a year," he added.

"This means that they will not only be able to feed their families, but also sell the surplus and generate extra income which is crucial for them to fully recover."

Graziano da Silva said Haiyan had destroyed 1.1 million tonnes of crops, along with 33 million coconut trees in a major farming region described by the Philippine government as among the poorest.

He said providing coconut farmers with other sources of income, such as helping them plant faster-yielding crops, was a top FAO priority in the six to eight years it will take for new coconut trees to start bearing fruit.