LONDON (Reuters) - The conflict in Afghanistan has reached "crisis proportions", with the resurgent Taliban present in more than half the country and closing in on Kabul, a report said on Wednesday.
If NATO, the lead force operating in Afghanistan, is to have any impact against the insurgency, troop numbers will have to be doubled to at least 80,000, the report said.
"The Taliban has shown itself to be a truly resurgent force," the Senlis Council, an independent think-tank with a permanent presence in Afghanistan, wrote in a study entitled "Stumbling into Chaos: Afghanistan on the brink".
"Its ability to establish a presence throughout the country is now proven beyond doubt," it said. "The insurgency now controls vast swaths of unchallenged territory including rural areas, some district centers, and important road arteries."
Senlis said its research had established that the Taliban, driven out of Afghanistan by the U.S. invasion in late 2001, had rebuilt a permanent presence in 54 percent of the country and was finding it easy to recruit new followers.
It was also increasingly using Iraq-style tactics, such as roadside and suicide bombs, to powerful effect, and had built a stable network of financial support, funding its operations with the proceeds from Afghanistan's booming opium trade.
"It is a sad indictment of the current state of Afghanistan that the question now appears to be not if the Taliban will return to Kabul, but when," the report said.
"Their oft-stated aim of reaching the city in 2008 appears more viable than ever."
NATO has a little over 40,000 troops operating in Afghanistan as part of the International Security Assistance Force. The United States and Britain are the largest contributors, with 15,000 and 7,700 soldiers, respectively.
Those numbers pale in comparison to Iraq where at the peak of operations there were nearly 200,000 troops on the ground and where around 160,000 remain.
While Iraq is showing the first signs of an improvement in security, Afghanistan's situation is becoming more precarious, Senlis argued, underlining the need for a rapid increase in troop numbers in a country that is larger than Iraq.
"In order to prevent NATO's defeat at the hands of the Taliban, a rejuvenated 'coalition of the willing' is needed," the report said, calling the proposal 'NATO Plus'.
"Every NATO state is mandated to contribute to this new force, with a firm level of commitment that will provide a total force size of 80,000."
Bolstering NATO's presence in Afghanistan, and getting member countries to contribute more, is expected to be a major issue on the agenda at a NATO summit in Romania in April.
Before then, Britain, which is responsible for security in the restive south of Afghanistan, where violence has been greatest, is expected to unveil new security strategies, including a possible increase in troops and proposals to deter Afghan poppy farmers from selling their crop to the Taliban.
Senlis said that without the troop "surge", and renewed efforts to win over the Afghan population and make reconstruction take hold, the country was in danger of falling back into the hands of the Taliban.
Editing by Kate Kelland and Michael Winfrey