* Claims filed for failure to complete shaft
* Shares in Shaft Sinkers fall more than 7 percent
(Adds detail, share price, no comment from Shaft Sinkers)
MOSCOW, Oct 5 (Reuters) - EuroChem, Russia's largest mineral fertilizer producer, said on Friday it had filed an $800 million compensation claim against Shaft Sinkers for delays to the building of a lift shaft at one of its potash projects.
EuroChem said it had filed the claim with the Swiss Chambers of Commerce in Zurich and the International Chamber of Commerce in Paris.
London-listed shares in Shaft Sinkers, which builds mine shafts, were down 7.2 percent by 1035 GMT.
EuroChem said it was seeking compensation for the delay to the start-up of potash production as a result of Shaft Sinkers' failure to complete construction of a cage shaft at its Gremyachinskoe deposit, the company said in a statement.
The deposit is one of two greenfield potash projects EuroChem is currently developing in Russia.
A Shaft Sinkers spokeswoman declined any immediate comment.
EuroChem has said the commissioning of Gremyachinskoe has been delayed to 2015 from late 2013 as a result of "difficult subsoil conditions".
(Reporting by Vladimir Soldatkin; Editing by Lidia Kelly and Jane Merriman)
Keywords: RUSSIA EUROCHEM/CLAIM