Police had become suspicious of the man and surrounded him, leading him to set off his explosives, the interior ministry said.
More attacks expected
Military officials said that they expect the Taliban to carry out more suicide attacks, because they are "unable to confront the security forces in conventional battle".
"Having security is of no use unless a massive amount of aid is invested into the community"
Justtone, Nottingham, UK
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"We have known that was [the attack] coming because the enemy knows they cannot stand up to the army and police toe-to-toe so they are going to go for soft targets," Colonel Tom Collins of the International Security Assistance Force (ISAF) said.
Ongoing efforts The Afghan defence ministry said on Monday that Afghan troops backed by Nato-led ISAF soldiers had killed 99 fighters in a four-day operation in Helmand, which is the heartland of the Taliban.
ISAF launched a separate operation in northern Helmand three weeks ago called Achilles, which is focused on stabilising an area around a hydropower dam so that the facility can be rehabilitated.
Surge in violence
There has been an increase in violent incidents in the past weeks, the ministry said.
Separately, the US-led multinational force announced it had arrested four men in the eastern province of Nangarhar in a compound containing rocket-propelled grenades and propellant.
They also arrested a man in Kunar province in a raid aimed at capturing a commander linked to bomb blasts and moving foreign fighters in the province.
A suicide bomb in Kandahar province late on Monday killed only the attacker, police said.