There is nothing official yet but it appears that Eli Lilly is the mystery bidder that has made an offer of around $6.1 billion for ImClone Systems.

ImClone had rather dramatically stated earlier in the week that the suitor had informed the US biotechnology that by a minute to midnight last night it would make a proposal or withdraw. A few hours before the witching hour, ImClone’s chairman Carl Icahn said that an offer has now been made that is not subject to financing or further due diligence.

He went on to say that while negotiations are underway, “the large pharma company has requested that ImClone not divulge its name until negotiations are completed”. However, the Wall Street Journal and pretty much every other news source is convinced that it is Lilly which has made the $70 per share bid.

The WSJ said that sources involved with the discussions had named Lilly as being the firm that was in advanced talks to buy ImClone. The Indianapolis-headquarted company said it will not comment on market speculation.

However there is certainly some logic to a Lilly link-up. The attraction of ImClone, indeed its only marketed product, is the cancer drug Erbitux (cetuximab) and Lilly already has a reasonable oncology franchise led by Gemzar (gemcitabine). Also this week, the firm got its third approval from the US Food and Drug Administration for Alimta (pemetrexed), this time as a first-line treatment against certain types of non-small cell lung cancer.

Still the battle for control of ImClone would appear to still have a long way to run. It all started when the company rejected an offer from Bristol-Myers Squibb, its US partner in developing and marketing Erbitux, of $60 per share for the 83% of ImClone it does not already own. B-MS then upped its bid to $62 and said it would take the offer straight to shareholders, which led to Mr Icahn describing that bid as "absurd".