The BBC estimate, which it said was based on conversations with more than 1,200 individual local sources in all districts of the South Asian country, was significantly higher than the most recent assessment by the NATO-led coalition of the Taliban's presence.
The coalition said on Tuesday that the Taliban contested or controlled only 44 per cent of Afghan districts as of October 2017.
Pakistan hands over 27 Taliban, Haqqani network suspects to Kabul
Afghanistan has been reeling over the past nine days from a renewed spate of violence that is adding scrutiny to the latest, more aggressive US-backed strategy to bolster Afghan forces battling the Taliban in a 16-year-old war.
A bomb hidden in an ambulance struck the city center and killed more than 100 people, just over a week after an attack on the Hotel Intercontinental, also in Kabul, which left more than 20 people dead, including four US citizens.
Although the BBC counted 399 districts in Afghanistan, the NATO-led force counted 407 districts. The reason behind the discrepancy was not immediately clear.
Senior Afghan politician says Taliban leadership not in Pakistan
The BBC study said the Afghan government controlled 122 districts, or about 30 per cent of the country. Still, it noted that did not mean that they were free from Taliban attacks.
"Kabul and other major cities, for example, suffered major attacks - launched from adjacent areas, or by sleeper cells - during the research period, as well as before and after," the report said.
Asked about the BBC's study, the Pentagon did not comment directly, but pointed to the latest figures by the NATO-led coalition asserting that about 56 per cent of Afghanistan's territory was under Afghan government control or influence.
The study by Britain's public broadcaster quoted a spokesperson for Afghan President Ashraf Ghani playing down the findings.
The BBC study also said Islamic State had a presence in 30 districts, but noted it did not fully control any of them.
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