UN head in polio eradication call
Mr Ban said he had written to the leaders of the four countries
The United Nations Secretary General has urged governments around the world to work towards eradicating polio.
Ban Ki-moon made his comments to delegates at the Rotary International Annual Convention at the National Exhibition Centre (NEC) in Birmingham.
The organisation has raised £151m($250m) since launching a campaign in 1985 to eliminate the disease.
He said polio is now only endemic in four countries, falling from 125 when the campaign began.
Mr Ban said he had written to political and religious leaders of the four remaining countries - Pakistan, Afghanistan, Nigeria and India - asking them to "protect their children and stop the virus wherever it survives".
We can either cut back on health expenditures and incur massive losses in lives... or we can invest in health and spare both people and economies
Ban Ki-Moon, United Nations Secretary General
The disease is often caused by poor sanitation and attacks the body's nervous system, in some cases causing paralysis within a matter of hours.
Children under five are most at risk although it can affect any age.
The advent of vaccines in the late 1950s effectively ended the threat to the developed countries.
"Now is the time to finish the job, I call on all governments around the world to help us," Mr Ban told Rotary members.
"Together we can fulfil the Rotarian vision and give future generations a polio-free world.
"At this time of global economic downturn, we find ourselves at a crossroads.
"We face multiple crises. We can either cut back on health expenditures and incur massive losses in lives and capacity for growth, or we can invest in health and spare both people and economies the high cost of inaction.
"The choice should be clear."
Anti-apartheid campaigner Archbishop Desmond Tutu was the keynote speaker at the convention on Thursday.
The event, which ends on 24 June, has been predicted to bring in £20m to the West Midlands region.