LONDON – NASCAR suspended Sprint Cup Series driver A.J. Allmendinger indefinitely Tuesday after a test of his backup urine sample confirmed the original positive result. The violation of NASCAR’s substance abuse policy puts Allmendinger’s future in NASCAR and at Penske Racing in doubt.

Allmendinger originally was suspended July 7 after failing a random drug test taken in late June. His backup “B’’ urine sample was tested Tuesday by Aegis Analytical Laboratories in Nashville, Tenn.

NASCAR officials announced the result and subsequent suspension Tuesday night.