In its latest move, Actavis had rejected the takover bid from Mylan last week. The bid was priced at US$15 billion, according to Reuters quoting an anonymous source familiar with the decision.

The cash and stock offer from Mylan for its larger rival came early last week had Actavis shares priced at US$120 per share. This comes after Actavis stopped its negotiations with Canadian pharmaceutical firm Valeant Pharmaceuticals International about a bid for about US$13 billion.

Currently, Mylan is not seeking any deal after Actavis share values rose significantly just last week above its US$120 per share bid, according to the source.

As for Actavis, its share price at closing last Tuesday was at US$121.68 on the New York Stock Exchange, which in turn values the company at above US$15.5 billion. The shares of Mylan increased by 3% to US$30.10, valuing the company at US$11.5 billion.

Both spokespersons for Actavis and Mylan declined to comment. Bloomberg News broke the story of the Actavis rejection of the Mylan offer. 

In another development, Actavis announced that it was in preliminary discussions with specialty pharmaceutical company Warner Chilcott.