Swiss pharmaceuticals giant Roche announced Wednesday it had launched a takeover bid for Illumina, a US company that specialises in life sciences. Roche said it had made \"multiple efforts\" to start talks with Illumina to negotiate a deal but the US firm had not been willing to enter \"substantive discussions\" \"Roche has therefore decided to promptly commence a tender offer to purchase all of the outstanding shares of common stock of Illumina for $44.50 (34.2 euros) per share in cash,\" said a company statement. This offer was \"full and fair value\" for the company, Roche chief executive Severin Schwan said in a statement. He added: \"It is our strong preference to enter into a negotiated transaction with Illumina, and we remain willing to engage in a constructive dialogue with Illumina to jointly develop an optimal strategy for maximizing the value of our combined business.\" The statement said the offer represented a 64 percent premium over Illumina?s stock price on December 21, 2011 and put the value of the San Diego-based company at $5.7 billion. A brief statement from Illumina acknowledged that Roche had made an \"unsolicited offer\" for the company. It said the board of directors would \"thoroughly review\" the proposal and make a recommendation \"in due course\" adding that it had asked share holders to take no action in the meantime.