A British man convicted of supporting the Taliban in the US has been freed after spending 11 years in prison, according to a statement by his family.

A picture shared on Facebook on Sunday showed Babar Ahmad at home with his father, a vocal figure in the decade-long campaign to free him.

The computer expert from London spent eight years in British custody without charge before he was extradited to the US, accused of running a website in support of the Afghan Taliban.

"Eleven years of solitary confinement and isolation in ten different prisons has been an experience too profound to sum up in a few words here and now," Ahmad was quoted as saying in the statement.

"In October 2012, I was blindfolded, shackled and forcibly stripped naked when I was extradited to the US," he said adding that "US and UK government officials" had treated him with respect after his release.

A judge sentenced Ahmad and another man, Talha Ahsan, in October last year, with Ahsan being released immediately because of the time he had already spent in custody. Ahmad received a 12,5-year sentence, but the ruling also took in to account the period he had already spent in jail.

Babar Ahmad is FREE! Read his first statement upon release here: http://t.co/Xh1lB0TzoB http://t.co/8cWfqLihzf — Azad Ali (@azadaliCCM) July 19, 2015

The pair had accepted a plea deal in which they accepted charges they had provided material support to the Taliban and fighters in Chechnya through websites they operated.