Farmers hit by Super Typhoon Haiyan face a "double tragedy" without urgent aid to clear land and irrigation channels and plant their crops, the Food and Agriculture Organization warned Wednesday.

The UN agency urged international donors to front at least $11 million (eight million euros) to help rural people in the Philippines clean farmland and de-silt irrigation canals rendered useless by this month's typhoon.

"The urgency of timing can't be overstated," said Dominique Burgeon, the director of FAO's Emergency and Rehabilitation Division.

"It would be a double tragedy if next spring farming families still needed to rely on continued humanitarian food assistance because we haven't been able to support them as they recover from this disaster."

The Philippine Department of Agriculture has asked the FAO to support the cash-for-work scheme covering some 150,000 hectares and 80 kilometres (50 miles) of communal irrigation canals, the FAO said.

It takes one person 10 days to clear a single hectare of farmland, it said. The funding will also go towards acquriring some 1,400 communal irrigation pumps.

The additional funds would come on top of $20 million already requested by the FAO to help Philippine farmers plant, fertilise, irrigate and maintain their crops to ensure the 2014 harvests.

Super Typhoon Haiyan left almost 7,000 people dead or missing when it swept through the central Philippine islands early this month.