Biopure ( BPUR ) said Wednesday that it will "likely need to conduct one or more" additional human tests of its Hemopure blood substitute in order to secure approval by the Food and Drug Administration.

The announcement, the latest in a series of delays and setbacks for the Cambridge, Mass.-based company, puts in doubt whether Biopure has enough time or money to complete its task. The company said earlier this year that it has enough cash to operate into September; however, that announcement came before Biopure said it would have to undertake more time-consuming and expensive clinical trials.

Biopure said Wednesday it will need an additional $7 million to keep operating through 2004, adding that it is "exploring various options to raise additional capital." Biopure now has $15 million in cash.

The news, delivered at the company's annual meeting Wednesday, drove the stock down 2.6%, or 4 cents, to $1.53 in early afternoon trading. The stock hit a 52-week high of $9.03 in August of last year.

"We strongly believe that Hemopure is both safe and effective when used appropriately," said Frank H. Murphy, the interim chief executive, in remarks prepared for the annual meeting. Murphy replaced Thomas A. Moore, who resigned as CEO in late February.

Murphy, however, added that the company has "substantial work to do" before the FDA will consider approving the company's application for the blood substitute. That's a stark contrast to the company's comments last summer, when it announced that the FDA needed answers to some questions that might require 30 to 60 days for a response. At the time, Biopure stated the FDA was not asking for any more tests on the blood substitute, for which the company was seeking approval for use in acutely anemic patients undergoing orthopedic surgery.

Since then, the FDA has asked for a lot more information and has told the company to conduct more animal tests as well. The company now says it expects to answer the FDA's questions "by early fall" and submit the results of four animal tests at that time. Three of these tests are proceeding, and the fourth is expected to start soon, Murphy said.

Murphy added that there has been no change in status for the company concerning a Wells Notice filed by the Securities and Exchange Commission on Dec. 22. The company responded Jan. 9 to the document, which says the SEC staff has made a preliminary decision to recommend that the agency bring a civil proceeding against Biopure. "We have cooperated with all SEC requests and are currently waiting for further communication," Murphy said. "We continue to believe the company acted properly in the matters investigated."