A Taliban suicide bomber detonated an explosives-packed car in Kabul on Saturday, killing at least six people near a compound where a controversial security pact between Afghanistan and the US will be debated, officials said.
Another 22 were injured when the vehicle blew up about 150 metres from a giant tent which will on Thursday host a meeting of elders on the future of US troops in the country after a NATO coalition pulls out in 2014.
"Initial information shows that unfortunately four civilians, one police and one soldier have been killed in today's attack," Afghan interior ministry spokesman Sediq Sediqqi told AFP.
"Twenty-two more, the majority of whom are civilians, have been injured," he added, noting that the toll may rise.
The Taliban claimed the attack later in the evening. The insurgent group had denounced the assembly, known as a 'Loya Jirga', and warned its members not to participate.
"No doubt the enemy will try its best to target the jirga, but I can say with confidence that our security forces are on high alert and will foil the enemy's desperate effort," said Sediqqi.
According to a statement issued by the interior ministry, the bomber was being pursued by security forces shortly before the explosion.
"The attacker driving a vehicle had been identified and was being pursued by security forces. He detonated himself after police opened fire on his vehicle."
Nasrullah, a witness, said: "I heard a big bang near the jirga site, and later saw ambulances carrying bloodied people. I saw at least three wounded in army uniforms."
Afghan President Hamid Karzai in a statement condemned the attack, blaming it on the "enemies of peace and progress", a term usually interpreted as a reference to the Taliban insurgents.