3/18/2013 5:00 AM PDT

Lindsay Lohan Faces MONTHS In Jail

Prosecutors will ask the judge in her criminal trial to throw the book at Lindsay Lohan and give her 240 days in jail if she's convicted of lying to cops in her June car accident case ... TMZ has learned.

Sources close to the case tell TMZ ... the L.A. City Attorney will be in court, lying in wait in the event Lindsay is convicted.  We're told if the jury finds her guilty, L.A. prosecutors will ask the judge to jail her ... because she would have squarely violated her probation in the jewelry heist case by breaking the law.

We're told L.A. prosecutors will ask for the maximum -- 240 days in jail.  Law enforcement sources tell TMZ ... if the judge sentences Lindsay to the max, based on the current formula and the fact that she's a repeat probation violator, Lindsay would actually serve between 60 and 90 days.

We're told the Santa Monica City Attorney -- which is prosecuting the main lying-to-cops case -- will not ask for additional jail time if Lindsay gets nailed with the max.

But here's the problem.  If Lindsay is convicted, she'd be placed on probation for ANOTHER 2 years, meaning if she violates any law, she could be hauled into court again, and possibly serve more jail time.