Polio virus has been detected in environmental samples in three separate cities in the country, the National Institute of Health said on Friday.

According to an NIH spokesperson, the virus was detected in environmental samples in Peshawar, Multan and Karachi.

The spokesperson added that the virus could have been transmitted from across the border. The virus is still spreading and could pose a risk to more children.

NIH said that eradication of polio was its top priority and the government considered it a responsibility to save future generations from this disease.

Pakistan and Afghanistan are the last two remaining countries where polio virus is still transmitted. The existence of the virus in these countries could also pose the danger of global resurgence, according to the World Health Organisation.

There is no cure for polio and it can only be prevented through vaccination.