Dr Rana Safdar of the National Institute of Health in the capital confirmed the new cases, saying all four cases were reported from the troubled northwest region, where militants often target polio teams.
This year's toll created a new ominous record, overtaking the 199 cases found in 2000. Maximum polio cases this year have been reported from the restive northwest region.
The new cases emerged ahead of new drive of anti-polio vaccination that will be launched on Monday to provide medicine to 35 million children in the country.
At least four polio volunteers were killed last month in Balochistan's capital Quetta.
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Pakistan government has come under criticism for doing little to eradicate the virus which is a threat to the world.
Security is the main reason for the spread of polio virus as vaccination cannot be organised in tribal areas where Taliban still control large areas.
They consider polio medicine as a conspiracy by the West to sterile Muslims. Peshawar is considered as hub of poliovirus.