Indian Drug maker Ranbaxy Laboratories is withdrawing all of its generic versions of antiretroviral drugs, which are supposed to restore the immune system, from the U.N. health agency's list of approved HIV medicines, saying it's uncertain they are biologically the same as the patented drugs, according to a statement made by the World Health Organization on Tuesday.

Ranbaxy claims that they found 'discrepancies in the documentation,' which meant that it was unable to prove in studies that its generic HIV treatments are equivalent to the original medicinest.

The company has already proposed dates to the health agency for the submission of reports on new studies of the drugs, WHO said. The first study is expected to be completed by December.

Earlier this year, WHO removed three other antiretroviral medicines manufactured by Ranbaxy and two more made by Cipla, another Indian firm, from its list of approved HIV treatments. Tests had failed to prove that these were the same as the patented versions.