KARACHI: Samples taken from sewage in different parts of Karachi and Lahore – the country’s most populated cities – have tested positive for the polio virus, officials confirmed on Tuesday.

The Prime Minister’s focal person on polio, Ayesha Raza Farooq, confirmed that an environmental sample from Lahore taken at the Main Outfall pumping station, and two from Karachi – one taken at Gadap and the other at Gulshan-e-Iqbal – have tested positive for the virus.

The samples collected were taken in April.

Earlier on Tuesday, Farooq chaired a meeting of the Prime Minister’s Polio Monitoring and Coordination Cell where the information was shared with stakeholders – including the World Health Organisation – in the country’s fight against polio.

However, Farooq says she was not “too concerned about (the environmental sample testing positive in) Lahore because there are no reported cases which means a high level of immunity has developed among the population so while the virus is still be circulating it is a low grade one.”

Related: WHO puts shackles on Pakistan over polio

“Yes, environmental samples show that the virus is still circulating in Lahore. We know of Karachi as there are already five positive cases reported from the city this year,” said Nima Saeed Abid, WHO representative and acting in-charge of the health organisation in Pakistan.

Out of the five cases reported from Karachi, three are from Gadap area.

However, Abid claimed that contrary to local television media reports, the WHO has not released any report in regard to sewage samples from Lahore or Karachi.

Last week, the WHO decided to impose strict travel restrictions on Pakistan to prevent the possible spread of the polio virus to other countries.

Pakistan currently stands at the top in the last three polio endemic countries in the world, which also include Nigeria and Afghanistan.

The WHO says the virus strain of polio found in Pakistan has affected as many as five countries over the past two years, becoming a serious threat to other countries.

The WHO has given Pakistan until June 1 to implement the restrictions.