Pakistani militant suspects held uncharged in Swat
Hundreds of militant suspects arrested by the security forces in the northern Pakistani region of Swat remain uncharged in custody, research by the BBC Urdu service has revealed.
Some of them have died under suspicious circumstances in the three years since the army announced it had ousted the Taliban from Swat.
The army says that only about 20-30 militants died in custody since 2009.
It insists that all of them died naturally after falling ill.
Swat army spokesman Colonel Arif said that all those who perished were provided with the best medical help.
The military argues that while deaths in custody have continued into 2012, their frequency has significantly decreased from previous years.
The research suggests that few militants end up being successfully prosecuted in the courts.
In 2009 the military drove the Taliban out of Swat, allowing thousands who had fled their repressive rule to return to the area.
While the overall level of militant violence was reduced - with the notable exception of the shooting of schoolgirl Malala Yousafzai in October - the army continues to be accused of custodial abuses, including extra-judicial killings.
The BBC Urdu research suggests that about 3,000 to 4,000 men have been arrested in Swat and six other districts within the Malakand division since 2008 on terrorism charges.
Correspondents stress that these figures are estimates, because no official figures have yet been released.
The research suggests that a lack of credible post-mortems in Swat has added to suspicions that hundreds of Taliban prisoners remain victims of systematic extra-judicial killings.
Similar claims were made in July 2010, when Human Rights Watch accused the army of carrying out 238 such killings in the Swat Valley since September 2009.
Unofficial sources say that the deaths in custody have increased substantially in recent months, however. Local newspapers and websites claim that the figures are much higher than admitted by the army.
A spokesman for the Human Rights Commission of Pakistan, Sher Mohammad Khan, said that most terrorism-related cases did not reach the courts either because the suspects were killed in custody or because they were released before the case came to trial.
Correspondents say that Swat is a case study for the rest of the country, underscoring how difficult it is to prosecute terrorist suspects in the aftermath of what was hailed as a successful military operation.
Prosecution rates are equally low in other Pakistani provinces.
Out of 250 militancy and terrorism cases registered nationally in the last three years, only 4% have been conclusive - the same rate as in Swat. The reasons are universally the same - lack of evidence.
Officials say that sketchy prosecutions combined with the reluctance of witnesses to give evidence in terrorism-related cases all contribute to the low conviction rate.
In Swat the case of a militant charged with beheading a policeman was eventually settled out of court without a sentence even though the evidence was stacked against him, the BBC Urdu research suggests.
The government says that it is trying to address the problem by changing the law to allow the evidence of a security officer to be sufficient to secure a conviction.