KABUL: When an 18-year-old dismounted his bicycle a couple kilometres outside the eastern town of Khost last week, his clothes flapped up, revealing a suicide vest to an alert farmer nearby.

Police soon surrounded the teenager and ordered him to remove his vest. He refused, grew increasingly agitated and eventually blew himself up, said Yaqoub Khan, police criminal director for Khost province.

No one else was hurt.

A suicide attacker on Monday waited on a roadside in eastern Paktika province, apparently biding his time for a target to appear. When an Afghan army convoy approached, the bomber blew himself up-- several meters (yards) ahead of the vehicles, said Mohammad Akram Akhpelwak.

He caused no injuries or damage.

The nature of the two would-be suicide bombers' deaths is strikingly common in Afghanistan. In sharp contrast to attacks in Iraq, scores of suicide strikes across Afghanistan have killed only the attacker, or a very few victims.

Nato said that as of last week, 97 suicide attacks this year have killed just 217 people-- a casualty rate four times lower than in Iraq.

''These suicide bombers are brainwashed in Pakistan. That's their only training. They don't know what they're doing,'' Khan said.

By comparison, 154 incidents involving suicide bombings in Iraq killed over 1,330 people this year, according to numbers compiled by The Associated Press.

Maj Luke Knittig, a spokesman for Nato's International Security Assistance Force, said Nato commanders have noticed how often suicide attacks in Afghanistan fail.

''We have certainly noticed that there have been a fair number that are pretty poorly executed and bungled, and of course they're all ill-conceived,'' he said.

Bruce Hoffman, a terrorism expert at Georgetown University, said suicide bombs allow attackers to get as close to their targets as possible and inflict the most damage. Bombers in Afghanistan apparently don't have a guide to route them to good targets, he said.

''It's a less sophisticated operation where the attraction of martyrdom is sufficient to recruit bombers,'' he said. ''They have the bombers, they just don't have the ability or inclination to steer the bomber to the most lucrative target.''

To be sure, suicide attacks have had deadly effect in Afghanistan. Suicide bombers in September killed 18 people outside the Helmand governor's compound, 16 people near the US Embassy and 12 people outside the Interior Ministry.

Two attacks in August and one in January killed 21 people each.

But the big, deadly attacks usually are organized by Al Qaida and involve Arab attackers or planners, said Gen Abdul Manan Farahie, the chief of the Interior Ministry's anti-terrorism department.

Most Taliban suicide attacks kill few people because the men called on to detonate themselves have no experience or training _ only a mullah in a Pakistani madrassa who orders him to do it, Farahie said.

He said most suicide attacks are planned in Pakistan.

''These people are not very experienced,'' he said. ''The Afghans doing the suicide attack, they were in the madressahs for five, six, seven months. They had no contact with their families, and they are under the psychological control of the mullahs. If they had contact with their families, they would say 'Don't do this’.”'

Overall, Nato last week said that only 30 per cent of all kinds of attacks-- including rockets, mortars and small arms attacks-- were ''effective'' from mid-October to mid-November. An effective attack is one that hurts or kills people or damages equipment, Knittig said.A US military spokesman, Lt-Col Paul Fitzpatrick, said that commanders do see trained, planned maneuvers in the field, but that many Taliban attacks fail because of a lack of experience.

''Certainly there are a fair number of failed attempts, and that's OK,'' he said. ''I hope they don't get better.''

There were two suicide attacks in 2003, six in 2004 and 21 in 2005, according to numbers compiled by the RAND Corp. think-tank.

That number has shot up this year, as Taliban fighters have increased attacks across the country. But Knittig said Nato and Afghan security forces are having increasing success moving against would-be bombers. He said joint Nato-Afghan operations have led to the dismantling of six suicide cells in the last three months.

Mohammad Ayoub, the provincial police chief of Khost, said police arrested a man two weeks ago after receiving a tip that he had bomb-making materials. Police found explosives and a remote control detonation device at his home, he said.

''Fortunately, people are giving us a lot of cooperation,'' Ayoub said. ''The people know that the suicide attacks are coming from outside the country. These people are not Afghans.''—AP