Slowbucks is a dirty liar for accusing 50 Cent of masterminding a plot to attack him and stealing his bling … so says 50 Cent himself.

50 just went on a preemptive tirade against Slowbucks saying the theft allegation is made up and Slowbucks is treading on dangerous territory spreading his story to TMZ and others.

As for Slowbucks … he claimed he was jumped on June 1 by 50’s goons who jacked his gold chain while 50 was onstage at the Summer Jam Festival in Jersey.

Slowbucks told TMZ … he’s not scared of 50 or his posse, telling us, “People know how I roll in the streets.”  He says 50 can keep the chain, saying he doesn’t want this to escalate into a Tupac/Biggie situation.