AJ Allmendinger suspended indefinitely from NASCAR as B sample tests positive

The 30-year-old Californian first tested positive earlier this month following a random test performed at Kentucky Speedway, which resulted in Allmendinger's suspension before the Daytona NASCAR Sprint Cup round a week later.

Allmendinger had the right to request a 'B' sample to be tested, which he duly did, the test taking place on Tuesday with the driver expected to have his own specialists as witnesses.

NASCAR has yet to announce the substance that caused the positive result. Allmendinger's management team confirmed following the 'A' sample test result that it was a stimulant.

While Allmendinger now faces an uncertain future, Sam Hornish Jr will continue to drive Penske's #22 Dodge at Indianapolis and Pocono, the team said.

"In accordance with NASCAR's Substance Abuse Policy, Penske Racing was notified today of AJ Allmendinger's positive B sample test," a statement from Penske Racing read.

"We respect NASCAR's policy and the process they have taken with this matter.

"Penske Racing is very disappointed with the result of the B sample test and will evaluate its course of action as it pertains to AJ over the coming week."

Allmendinger's management team issued a statement on Tuesday night saying they have hired an independent laboratory to try to identify any substances that may have contributed to both tests drawing positive results.

"This was not the news we wanted to hear and we will work to get to the source of what may have caused this," said Tara Ragan, vice president of Walldinger Racing Inc.

"To that end, we have secured the services of an independent lab to conduct thorough testing on every product within AJ's home and motor coach to find what might collaborate with his test, which created results that were within nanograms of accepted standards.

"We are working closely with NASCAR and Penske Racing to identify the next action steps in this process. We continue to be extremely grateful by the breadth and scope of support for AJ from his fans and partners.

"We would like to again thank NASCAR, Penske Racing and all our sponsor partners for the open communication, and for helping us at every step in this process. We expect to have further updates in the upcoming days."