Britain promised to double its funding on Friday to fight polio if other donors also upped their contributions to eradicate the crippling disease, Reuters reported. British Prime Minister David Cameron issued a joint statement with philanthropist Bill Gates pledging to increase UK government funding by 20 million pounds ($32 million) to 40 million pounds a year for two years. The extra funding will be given on a matching fund basis, which means that for every $5 pledged by others from January 1, 2011 to December 31, 2012, Britain will increase its support by $1, up to a maximum of 40 million pounds over the two years. The number of polio cases has been reduced by 99 percent in the past two decades and the disease is now close to being only the second in history -- after smallpox -- to be wiped out. Gates, whose $34 billion Gates Foundation seeks to improve health in poor countries, told Reuters this week he thought polio could be stopped in all but one endemic region in the next three years if donors and national governments focused on getting vaccines to those who need them. Gates said his foundation was committing an additional $102 million to efforts to stamp out the disease. Cameron, who is attending the World Economic Forum in the Swiss resort of Davos, said it was a "once-in-a-lifetime opportunity to rid the world of the evil of polio". The new funds from Gates and Britain, as well an extra $50 million from the Crown Prince of Abu Dhabi announced this week, are intended to help fill a funding gap of $720 million for the fight against polio. The virus, which attacks the nervous system and can cause irreversible paralysis within hours of infection, is currently endemic in four countries -- Afghanistan, India, Nigeria and Pakistan -- and there were outbreaks of the disease last year in Angola, the Democratic Republic of Congo and Tajikistan. Children under five are the most vulnerable, and the Global Polio Eradication Initiative, spearheaded by the World Health Organisation (WHO), is running vaccination campaigns in high risk countries to try to prevent its spread. Polio vaccines are made by several companies and the WHO has certified various types made by GlaxoSmithKline , Novartis, Sanofi-Aventis, Panacea Biotec and others for use in its immunisation campaigns. -- SPA