It is possible that local health officials are concealing suspected cases of human bird flu, the Wall Street Journal reported, citing a source familiar with the topic. This appears to tally with a sharply worded statement that appeared on the Ministry of Health's website on Tuesday reiterating warnings that cover-ups and delays could facilitate the spread of the disease. However, ministry spokesman Mao Qunan said there was no evidence of local authorities suppressing information relating to the H5N1 virus, although he admitted that problems have been experienced with hospitals not reporting cases of severe pneumonia that could be bird flu. Officials in Beijing have been working closely with the World Health Organization, reporting confirmed cases of the disease and allowing foreign scientists to take part in research. But some international experts have long warned that the real challenge is in ensuring health officials in remote areas are prompt in reporting cases to Beijing. So far there have been 17 confirmed human cases of bird flu, 12 of which have been fatal.