BERLIN, Sept 14 (Reuters) - U.S. electric carmaker Tesla TSLA.O plans to raise production at its German plant for the rest of the year due to strong sales, the head of the Gruenheide factory told Germany's DPA news agency on Sunday.

“We currently have very good sales figures and have therefore revised our production plans for the third and fourth quarters upwards,” André Thierig, manager of the Gruenheide plant outside Berlin, told DPA.

Germany is a tough market for Tesla due in part to stiff competition from Chinese rivals. Elon Musk's political activity may also have affected demand, say analysts.

In July, Tesla's sales volumes more than halved from a year earlier to 1,110 cars and in the January-July period, sales were down 57.8%, according to the KBA road transport agency.

Thierig said the company was seeing positive signals for all markets the factory supplies, adding that went beyond Germany.

"We supply well over 30 markets and definitely see a positive trend there,” he told DPA.

(Reporting by Madeline Chambers;Editing by Elaine Hardcastle)

((Madeline.Chambers@thomsonreuters.com; +4930220133578;))