The additional charge relates to irregularities in Romanian Halep's Athlete Biological Passport (ABP), based on an assessment of her profile by an independent ABP Expert Panel.
The former Wimbledon and French Open champion, has already been provisionally suspended since October 2022 after testing positive for banned blood-booster roxadustat at the US Open last year.
Halep has denied knowingly taking the banned substance and said she has evidence which proves low quantities of the anti-anaemia drug entered her body because of an authorised supplement that was contaminated.
Halep called on tennis' anti-doping body to allow her to clear her name, questioning the long delay in her doping hearing after being denied the right to be heard by an independent court.
"Not only has my name been soiled in the worst possible way, but I am facing a constant determination from the ITIA for a reason that I cannot understand, to prove my guilt while I haven't EVER even thought of taking any illicit substance," said the Romanian athlete in a statement on Twitter.
Halep, who has strongly denied knowingly taking the banned substance, said she has evidence to show that small amounts of the anaemia drug entered her system from a licensed supplement that was contaminated.
"I tried two times to have the opportunity to be judged by an Independent Tribunal but the ITIA has constantly found reasons to postpone.
"The only thing I hope for, at this point, is to have the possibility to finally access the independent and impartial judges in a Tribunal, that will give me the chance to prove my innocence," she added.
"I have full trust in justice and I look forward to finally being able to present my case at my hearing that is scheduled at the end of May, after several delays by the ITIA."
"We understand that today's announcement adds complexity to an already high-profile situation...
"We have remained committed to engaging with Ms. Halep in an empathetic, efficient, and timely manner," said Senior Director for Anti-Doping at the ITIA, Nicole Sapstead, in a statement.
"It would be inappropriate for us to comment on specifics until the conclusion of the process, but we will continue to engage with the Sport Resolutions independent tribunal and Ms Halep's representatives as expeditiously as possible."
