Taliban fighters in Dhani-Ghorri in northern Afghanistan. Photograph: Ghaith Abdul-Ahad for the GuardianBritish-based men of Afghan origin are spending months at a time in Afghanistan fighting Nato forces before returning to the UK, the Guardian has learned. They also send money to the Taliban.

A Taliban fighter in Dhani-Ghorri in northern Afghanistan last month told the Guardian he lived most of the time in east London, but came to Afghanistan for three months of the year for combat.

“I work as a minicab driver,” said the man, who has the rank of a mid-level Taliban commander. “I make good money there [in the UK], you know. But these people are my friends and my family and it’s my duty to come to fight the jihad with them.”

“There are many people like me in London,” he added. “We collect money for the jihad all year and come and fight if we can.”

His older brother, a senior cleric or mawlawi who also fought in Dhani-Ghorri, lives in London as well.

Intelligence officials have long suspected that British Muslims travel to Afghanistan and Pakistan each year to train with extremist groups.

Last year it was reported that RAF spy planes operating in Helmand in southern Afghanistan had detected strong Yorkshire and Birmingham accents on fighters using radios and telephones. They apparently spoke the main Afghan languages of Dari and Pashtu, but lapsed into English when they were lost for the right words. The threat was deemed sufficiently serious that spy planes have patrolled British skies in the hope of picking up the same voice signatures of the fighters after their return to the UK.

The dead body of an insurgent who had an Aston Villa tattoo has also been discovered in southern Afghanistan.

British military officials say there have been no recent reports of British Taliban in Helmand in southern Afghanistan and that the overwhelming majority of foreign fighters are Pakistanis. Not since John Walker Lindh, the so-called American Taliban, was captured in late 2001, has the US admitted to having successfully captured an insurgent from a western country.

In the main US-run prison near Bagram airfield, there are just 50 “third country nationals” being held, a spokeswoman said.

“Most of these are Pakistani, with small numbers from other countries in the region,” she said.

According to a senior officer at the National Directorate of Security, Afghanistan’s equivalent of MI5, foreign fighters tend to be Arabs, Chechens, Pakistanis or from central Asia’s former Soviet republics such as Tajikistan and Uzbekistan.