Momenta Pharmaceuticals has started legal proceedings against pharmaceutical giant Teva over a patent dispute involving a generic version of anti-clotting medication Lovenox.

The US-based company has alleged that Teva violated two patents relating to the medication. Lovenox itself is a generic version of the Sanofi-Aventis made original, approved in the US in 1993.

The US Food and Drug Administration approved generic version of the drug produced by Momenta and Novartis AG in July 2010, and Momenta is also facing legal action itself for patent infringement.

Teva confirmed it is facing legal action from Momenta and Sandoz, a Novartis unit, but has alleged that its version of the drug does not infringe on either patents.