Sirius Minerals signs deal with China's Huaken for North Yorkshire potash mine

Once the potash mine is fully operational, Sirius will supply as much as 500,000 tonnes a year under an “offtake agreement”, a deal made before a mine goes into production.

The deal with the China business follows an agreement with a US fertilizer group which tripled its seven-year deal in August to 1.5m tonnes of polyhalite a year.

Sirius has been seeking financiers for the development of the world’s largest deposit of polyhalite, a type of fertilizer, in the North York Moors National Park but the project is not expected to show an operating profit until 2019.

The mine is estimated to cost about £1.5bn to build and will produce about 13m tons of polyhalite a year, according to the latest study. A new feasibility study is expected to be completed in January.

Shares in Sirius were up 2.07% to 14.29p at 0915 GMT.