At least five bidders are vying for the generics operation of German pharma firm Merck KGaA, The Wall Street Journal reports. The bids, from other generics firms as well as from private equity, range from $5-$6.5 billion, the newspaper said.Generic drug firms entering bids by this week’s Monday deadline were Teva Pharmaceutical, Mylan Labs, Actavis Group and Ranbaxy Labs. Private-equity firms Bain Capital and Apax Partners made a joint offer, according to the WSJ report. And Indian generics maker Cipla is advising a second offer from a consortium consisting mostly of private-equity companies.Merck KGaA started exploring options for the generics unit, which had 2006 sales of $2.4 billion, last month. Final bids are due by the end of April, a source told the newspaper, with Merck due to compile a short list of suitors by next week. Bear Stearns is handling talks with potential buyers.A successful bid by Ranbaxy would make it the third-biggest biggest generics firm, behind Teva and Novartis’ Sandoz unit.