Image caption The new funding will help buy vaccines and conduct immunisations

The UK government is doubling the amount of money it gives to the global campaign to wipe out polio to £40m ($63.3m) this year and next.

The money for the Global Polio Eradication Initiative (GPEI) should mean an extra 45m children can be vaccinated.

Over the last 20 years, polio cases have been cut by 99%, and the condition is close to being eradicated.

It is still endemic in Afghanistan, India, Nigeria and Pakistan.

And it is present in over a dozen countries altogether.

The UK currently donates £20m each year to GPEI, which is led by the World Health Organization (WHO).

The extra money will be given on the understanding that routine immunisation is strengthened in the countries affected.

The UK government has also called for each dollar of its funding to be matched by $5 from other donors.

The Bill & Melinda Gates Foundation is to donate an extra $102m (£64.3m) to the GPEI.

'Aggressive programme'

The UK Prime Minister, David Cameron said that it was possible to wipe out polio completely.

"We have the vaccines and the tools to do it. All that's missing is a real and sustained political will to see this effort through to the end."

"Eradicating polio requires innovative thinking and political will Bill Gates

Andrew Mitchell, International Development Secretary, added: "Britain is at the forefront of the fight against polio.

"We have already provided funding for 1.2 billion doses of polio vaccine for children over the past two years and our increased commitment means many millions more will be protected from this terrible disease."

Bill Gates said: "Eradicating polio requires innovative thinking and political will, as well as funding from a range of donors, to support an aggressive programme that will get the job done."

The GPEI is a public-private partnership, spearheaded by the WHO. It is funded by the US, UK and Indian governments, Rotary International and the Bill and Melinda Gates Foundation.