A Pakistan student arrested by Britain on allegations of terrorism has described his detention as 'mental torture'.
Tariq ur Rehman has returned home to Pakistan after the allegations were dropped in a deepening diplomatic row which saw twelve people arrested in an embarrassing blunder for Britain.
British authorities failed to produce enough evidence to back up the terror charges but insisted on deporting the students anyway - sparking a diplomatic row between the UK and Pakistan.
'I fail to understand still why they kept us under detention,' Rehman, apparently the first to be sent home, told reporters in brief comments at the Islamabad airport.
'We were accused of being Islamic extremists.'
The twelve people, most of them Pakistanis in Britain on student visas, were arrested in dramatic daytime operations across England on April 8.
The arrests were rushed in part because one of the top counter-terrorism officers inadvertently exposed details of the operation to a photographer outside Downing Street.
Gordon Brown trumpeted the arrests as the disruption of 'a very big terrorist plot' - making the failure to charge anyone all the more humiliating for himself and Britain.
Britain has said it wants to deport all but one of the men on national security grounds, prompting protests from Islamabad. The Home Office has refused to say what the men are accused of or how long they might be held before deportation.
'I think the mental torture is worse than physical torture,' Rehman told reporters.
He declined to say if he would sue Britain. It is not clear what he was studying in the UK.
Britain's embassy in Islamabad said Rehman had agreed to voluntary deportation.
High Commission spokeswoman Jennifer Wilkes said it might issue a statement on Rehman's case later today.
Some of the students have lawyers and are fighting to stay and resume their studies in Britain.
Several students' families in Pakistan have begged British officials to allow them to finish their degrees, saying their futures are at stake.
Pakistan Foreign Ministry spokesman Abdul Basit, while noting Rehman had returned to Pakistan voluntarily, said his government stood behind the students who were fighting to stay in Britain.
'We still want our students to be released. We still want them to be allowed to continue their studies,' he said. 'We support them.'
The detainees' case has also caused outrage among British Muslims, with supporters holding vigils and protests.