By Charles Haviland
BBC News, Kabul
More than half of suicide bombers used by the Taleban for attacks in Afghanistan are not Afghans, the UN has quoted a Taleban commander as saying.
The attacks are usually aimed at the military but often kill civilians
In a report on Afghan suicide attacks, it quotes the same man as saying more than 80% of the bombers are recruited, trained or sheltered in Pakistan.
It notes a steep increase in the number of incidents over the past two years.
The UN has released the report to coincide with the sixth anniversary of the country's first suicide attack.
The mujahideen leader Ahmad Shah Massoud was killed in that attack.
But it was only after 2005 that suicide strikes became common here, used by the Taleban in their insurgency.
Last year there were 123 and this year 103 by the end of August.
During the first six months of the year such attacks killed 193 people - 121 of them Afghan civilians, 62 Afghan security forces, and 10 foreign troops.
The authors believe many attackers are opium addicts, and many others orphans
The report says Afghans should accept the fact that their compatriots do mount such attacks. In the past Afghan leaders have sometimes said Afghans simply do not commit suicide.
Nonetheless, the UN quotes a senior Taleban commander as saying that more than half the attackers here are foreign, coming mainly from Pakistan and also Arab and Central Asian states. It says the commander's views "have been verified".
Families in the dark
The UN says that in several ways, suicide attackers in Afghanistan differ from those in other countries.
They tend to be poor and little educated, very often groomed in madrassas in Pakistan's tribal areas.
None have been women, and there have never been pre-attack statements from them or acts to venerate their families.
Indeed, often the families are unaware their son has died in a suicide mission.
Recently President Hamid Karzai pardoned a teenage boy who had failed in a bid to blow up a provincial governor.
His father had sent him to a Pakistani madrassa but had no idea he had come back to Afghanistan having been groomed for a suicide attack.
Of those interviewed, some said they had been duped or even told that that they would not die in the bomb blast and would receive a financial reward
The authors believe many attackers are opium addicts, and many others orphans.
The report says the authorities here are now preventing many such attacks and that even the ones that succeed tend not to kill many people. However, 80% of those they do kill are civilians, even though all the attacks appear to be aimed at Afghan or foreign security forces, or Afghan government targets.
The authors of the report interviewed 23 failed attackers held in an Afghan prison, ranging from a boy of 15 to a man in his 50s. Of these, 21 were Afghan. Some were awaiting trial but none, said the UN, had recourse to any legal counsel.
Of those interviewed, some said they had been duped or even told that that they would not die in the bomb blast and would receive a financial reward. Those coercing them, for instance by threatening to behead them, rarely go on to mount suicide attacks themselves.
But others were willing attackers, angered by the presence of foreign troops in Afghanistan, by the civilian deaths caused by them, or by what they saw as the corruption of the Afghan government.
Many said they were sorry that suicide attacks killed civilians but the attackers believed these ordinary people would go to heaven as martyrs.
The report urges more troop contributions by Muslim countries
The UN says suicide attacks here tend to diminish people's faith in the Afghan state, and cites polls as saying just over a tenth of Afghans believe such attacks are always or sometimes justified.
The Special Representative of the UN Secretary-General in Afghanistan, Tom Koenigs, said that while suicide attacks tended to be militarily ineffective, they could have a big propaganda effect, bringing publicity to the Taleban.
An example was a bomb outside the Bagram air base in February which killed over 20 civilians when US Vice-President Dick Cheney was inside.
Mr Koenigs said that in order to try to undermine the attackers' motivations, it was vital that foreign forces in Afghanistan do their utmost to reduce the civilian casualties they were causing, and that Afghan forces take on more of the burden of providing security.
He also said it would be good if more Muslim countries could contribute troops to the Nato-led force here, Isaf. Currently the only Muslim-majority countries in Isaf are Turkey, Azerbaijan and Albania.