By Toni Clarke
The offer would top an unsolicited earlier bid from Bristol-Myers Squibb Co
Bristol-Myers declined to comment.
Carl Icahn, the billionaire investor and chairman of ImClone's board, said in a statement he has had several conversations with the chief executive officer of a large pharmaceutical company.
As a result, the pharmaceutical company has submitted a proposal, subject to due diligence but not to financing, ImClone said.
ImClone, which makes the cancer drug Erbitux, said no determination has been made as to whether $70 a share would be adequate. The company's European partner is Merck KGaA
Merck declined to comment.
"It's good to get some more competition into the bidding process," said Eric Schmidt, an analyst at Cowen & Co. "In the end it probably goes to Bristol as they have the most incentive and are the most needy. This may force their hand."
ImClone's shares rose 7.5 percent to $68.41 on Nasdaq. Earlier they hit a 52 week high of $68.89.
(Additional reporting by Debra Sherman in Chicago and Patricia Gugau in Frankfurt)
(Editing by Gerald E. McCormick, Dave Zimmerman)