GENEVA - The U.N. health agency is facing a funding shortfall that is undermining efforts to eradicate polio within two years, its new chief said Tuesday.

The World Health Organization will be forced to slash polio immunization and surveillance programs unless it receives $210 million, said Director-General Dr. Jong-wook Lee.

The polio virus is now circulating in only seven countries, down from over 125 when the WHO-led Global Polio Eradication Initiative was launched in 1988. The world had 1,919 cases of polio reported last year, down from the estimated 350,000 cases when the campaign began.

WHO has set a 2005 target date to eradicate polio and said it needs the money for a final offensive against the disease.

It is focusing its attention on India, Nigeria, Pakistan and Egypt, the main countries still affected. The others are Afghanistan, Niger and Somalia.

"We have a great opportunity," said Lee. "For the first time this century, we can eradicate a terrible disease from our planet.

"Polio eradication is a top priority. I want to see this disease gone once and for all," said Lee. "We have eliminated it from almost every country in the world. Now is the time to boost our action and resolve, and wipe it out everywhere."

Lee, who came into office last week, is a South Korean tuberculosis expert who previously ran WHO's Stop TB program. He was elected in January by the executive committee of the 192-nation agency.

He replaced Dr. Gro Harlem Brundtland, a former Norwegian prime minister, who announced last year that she did not want a second five-year mandate.

Lee has picked Dr. David Heymann, the expert who led the WHO response to SARS, to step up the fight against polio. Despite the huge reduction in cases and their limited geographical spread, the world should not underestimate the continuing global threat posed by polio, Heymann said.

"Just as with SARS, polio knows no boundaries," said Heymann. "In January a child was paralyzed by polio in Lebanon for the first time in 10 years. That virus traveled from India.

"Unless we stop transmission in the remaining polio-endemic countries, polio will spread to other countries and paralyze children, potentially reversing the gains already made."

In the past 12 months, polio viruses have also spread from Nigeria to neighboring countries which had been polio-free, said WHO.

Polio attacks the central nervous system, causing paralysis and, occasionally, death. It is transmitted through food or water contaminated by the feces of an infected person. There is no cure.

Once an epidemic, the disease has disappeared from much of the planet.

Health officials say the virus spreads most easily in urban slums and remote villages, where overcrowding, poor sanitation and nutrition, and a lack of health care services are problems. Indifference toward vaccinations, transient communities and religious and ethnic tensions have complicated prevention programs, they say.

The only major disease to be successfully eradicated under a WHO-sponsored vaccination program was smallpox, which saw its last case in 1978.

To be declared disease-free, a country must have no new cases for three years.