China is to invite experts from the World Health Organisation to probe possible human cases of bird flu.Beijing said it could not exclude that a 12-year-old girl who died last month had succumbed to the lethal H5N1 strain of the virus. WHO officials will also look into cases of pneumonia in a province that has reported bird flu outbreaks. Medical advice and free checks are being offered to people in affected areas. In a badly hit northeastern part of the country, the government is hoping to cull all poultry by the end of Sunday. On Monday hundreds of health officials will gather in Geneva to try to work out a global plan to stop the virus sparking a human pandemic that could kill millions. Hosted by the WHO, it will be the largest such meeting since bird flu began to spread in 2003. Talks will cover the possibility of setting up a global fund to help fight the disease and creating regional stockpiles of antiviral drugs.