North American potash stocks swell 7 pct in October

* Inventories 43 pct above 5-year average

* Contract delays with China, India cause supplies to grow

Nov 20 (Reuters) - North American potash inventories at the producer level, a key indicator of market sentiment, climbed i n October, according to the world's top producer of the crop nutrient, Potash Corp, highlighting slumping demand in top offshore markets.

Stockpiles of potassium chloride, the crop nutrient more commonly known as potash, swelled 7.2 percent to 2.5 million tonnes, according to data posted on Potash Corp's website.

Inventories of the crop nutrient at the producer level now stand 43 percent above the previous five-year average.

Spot potash prices eased to roughly $470 per tonne.

Potash supplies have swollen as top global consumers China and India delay signing new supply contracts with Canpotex, the offshore marketing company owned by Potash Corp, Agrium Inc and Mosaic Co.

Last Wednesday, Potash Corp said it would shut two of its Canadian mines for eight weeks each between December and February, to match supply closer to demand.

The vast majority of the potash produced in North America is mined in the Western Canadian province of Saskatchewan, where Potash Corp is headquartered.