Rapper Young Buck has been threatened with a return to jail after failing to attend two court-ordered drug tests as part of his probation.

The former G-Unit star was jailed in 2012 on gun possession and tax evasion charges after police officers found a firearm at his Tennessee home during a bankruptcy raid in 2010.

The hip-hop star, real name David Brown, walked free in October (13) and is required to submit a series of urine tests as part of his probation, but editors at Tmz.com report he has missed the last two appointments.

The performer reportedly admits his mistake in court documents, but has been warned by his probation officer he will face jail time if he misses a third test.