A suicide bomber detonated his explosives near Pashtunistan Square in Kabul city center on Monday killing at least six people and wounding 20 others, close to where hundreds of protesters had gathered.
The explosion took place close to the busy circle, which is in the same area as the ministries of finance and justice and close to the Presidential Palace.
The explosion happened just after 1.30pm local time.
According to a ministry of interior spokesman, a suicide bomber detonated his explosives after being spotted by police. He said at least six people were killed and 20 wounded, including policemen, in the blast.
Hundreds of protesters have been gathered in the area throughout the day after marching to the Presidential Palace early Monday in protest over the lack of security and ongoing Taliban threats in Ghazni and Uruzgan provinces.
Security had been tightened from early morning in the area, with most roads closed to traffic, after protesters started gathering near the Presidential Palace.
The ministry of interior said in a statement that the suicide bomber blew himself up at a check point in the area.