A mass vaccination campaign against polio has been launched in China after it was confirmed that the virus had spread from Pakistan.
So far, nine cases of wild poliovirus 1, which has broken out in China for the first time since 1999, have been found in the region.
The infectious disease has been genetically linked to the virus currently circulating in Pakistan.
It is thought that the spread to China was caused by inadequate immunisation activities in federally administered tribal areas, including Khyber, the World Organisation (WHO) said in a statement.
The WHO rates the risk of further international spread of wild poliovirus from Pakistan as "high", particularly given the expected large-scale population movements associated with Umrah and the upcoming Hajj.
Pakistan is coming towards the end of its three-day nationwide polio eradication campaign, which is pushing the administration of anti-polio drops to children under the age of five.
Officials said on Monday that special arrangements have been made to reach 32.7 million children in the country with 39 million doses of polio vaccine, the Pakistan Observer reports.