MOSCOW, April 5 (Reuters) - Belarus's potash monopoly has raised prices by 13% in a potash supply contract with India signed earlier this year, the Belarus Potash Company (BPC) said on Monday, signalling a stronger outlook for potash producers.

BPC, a trading arm of Belaruskali, the world's largest producer of the crop nutrient, signed its annual potash supply contract for 800,000 tonnes with India's largest importer of the product, Indian Potash Limited, in January.

BPC renegotiated the contract price to $280 per tonne from the previous $247 a tonne on a cost and freight basis "within the framework of close partnership," it said in a statement.

BPC competes with Mosaic and Israel's ICL among other producers. (Reporting by Maxim Rodionov; writing by Alexander Marrow and Polina Devitt. Editing by Alison Williams and Mark Potter)