Bean sprouts from the German state of Lower-Saxony are suspected of being the source of the deadly E. coli outbreak which has killed 22 people, the region\'s agriculture ministry said Sunday. There was no definite proof as yet but \"signs are so strong we recommend that consumers do not eat bean sprouts,\" regional agriculture minister Gert Lindemann told a news conference. Initial test results from a farm producing the bean sprouts, on the outskirts of Luenerburg, showed contamination by the bacteria, the minister said. More tests were needed however to be sure, he added. The bean sprouts are from a variety of products, the ministry indicated in a statement. News of the possible breakthrough came as the death toll climbed to 22, with the latest figures from the European Centre for Disease Prevention and Control (ECDC) adding three victims to the previously confirmed 19. All but one of the deaths occurred in Germany, the source of the enterohaemorrhagic E. coli (EHEC) outbreak which has affected 12 countries. The other victim died in Sweden. German Health Minister Daniel Bahr, who was on Sunday visiting Hamburg\'s Eppendorf University clinic where many of the region\'s EHEC patients are being treated, has warned that the source of infection could still be active. \"Food health officials are working around the clock to identify the source of the infection,\" Bahr told the Ruhr Nachrichten newspaper on Saturday. \"But from earlier outbreaks we know that we can\'t always identify the source. \"It can\'t be ruled out that the source of infection is still active,\" he added, pointing to the need for continued vigilance as authorities still counsel against eating raw tomatoes, lettuce and cucumbers. Speaking to Bild am Sonntag, Bahr said also the situation in a number of north German hospitals, especially Hamburg and Bremen, was \"difficult\" because of the high number of admissions, adding that other hospitals would be called upon to help. Related article: Women \'more at risk from E. coli outbreak\' Cases of E. coli poisoning have also been reported in more than 12 other countries, including Austria, Britain, the Czech Republic, Denmark, France, The Netherlands, Norway, Spain, Sweden, Switzerland and the United States. Each was related to German travel. Meanwhile, several German scientists Sunday suggested the outbreak could be linked to bacteria found in biogas plants. Biogas, or methane, is produced by the anaerobic digestion or fermentation of biodegradable materials such as manure, sewage and green waste. \"There are all sorts of bacteria which didn\'t exist before which are now produced in biogas fermentation tanks,\" Bernt Schottdorf, a medical analyst, told Welt am Sonntag newspaper. \"They crossbreed and mix with one another -- what goes on precisely hasn\'t really been studied,\" he said, adding that 80 percent of the production waste finds its way back onto fields as fertiliser. Ernst Guenther Hellwig, head of the veterinary and agriculture academy in Horstmar-Leer, said that because it had rained very little in the spring it was possible such fertilisers had not been washed off growing plants. \"Dangerous bacteria could be brought onto the fields this way and could contaminate vegetables,\" he said. The WHO has identified the bacteria as a rare E. coli strain never before connected to an outbreak of food poisoning. It is said to be extremely aggressive and resistant to antibiotics. The ECDC reported 1,605 cases of EHEC infection and 658 cases of the associated condition haemolytic uraemic syndrome (HUS) on Sunday.