By Toni Clarke

The offer would top an unsolicited earlier bid from Bristol-Myers Squibb Co of $60 a share, which ImClone says is too low.

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 . Its U.S. partner on the drug is Bristol-Myers.

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)