LONDON - Health experts say time is running out for German investigators to find the source of the world's deadliest E. coli outbreak, and some have been surprised - even shocked - at lapses in the German investigation.

German health officials are still looking for the cause of the outbreak that began May 2. So far, the super-toxic strain of E. coli has killed 24 people, infected over 2,400 and left hundreds hospitalized with a serious complication that can lead to kidney failure. New cases are still being reported every day - 94 more in Germany yesterday.

"If we don't know the likely culprit in a week's time, we may never know the cause," Dr. Guenael Rodier, the director of communicable diseases at the World Health Organization, said yesterday.

Experts say the outbreak could have been spotted sooner with better medical detection and immediate interviews with patients about what they ate.

German officials accused Spanish cucumbers of being the culprit last week but had to retract when the cucumbers had a different strain of E. coli. On Sunday, they blamed German sprouts, only to backtrack a day later when initial tests were negative.

Yesterday, the EU health chief warned Germany against issuing any more premature - and inaccurate - conclusions about the source of contaminated food. EU health chief John Dalli told the EU parliament in Strasbourg that information must be scientifically sound and foolproof before it becomes public.

Rodier said the contaminated vegetables have probably disappeared from the market and it would be difficult for German investigators to link patients to contaminated produce weeks after they first became infected.

Other experts were more critical of the German investigation.

"If you gave us 200 cases and 5 days, we should be able to solve this outbreak," said Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota, whose team has contained numerous food-borne outbreaks in the United States.

Osterholm described the German effort as "erratic" and "a disaster" and said officials should have done more-detailed patient interviews as soon as the epidemic began. He also disputed the idea it might be impossible to find the outbreak's source.

"To say we may never solve this is just an excuse for an ongoing bad investigation," he said. "This is like a cold murder case where you go back and re-examine the evidence."