Aljazeera's correspondent in Kabul reported that two people were killed and five wounded when a hand grenade exploded in an internet cafe in central Kabul.
The cafe is at the front of a guest house used by Westerners in the heart of the city.
"Two people have been killed and five wounded by the bomb blast," Kabul police chief Akram Khakrizwal told Reuters.
Speaking to reporters in front of the damaged cafe, he later described the blast as an act of terrorism.
Kabul has seen occasional bomb blasts against NATO-led peacekeepers, since US-led forces overthrew the Taliban government in late 2001.
The deadliest attack was in September 2002 when more than 20 people were killed and scores wounded by a car bomb on a busy city street.
Four German soldiers were also killed and 31 wounded in June 2003 by a bomb-attacker. The most recent blast was two weeks ago but it caused no casualties.
No one had claimed responsibility for Saturday's explosion and it was too early to say who may have been behind it, another police official said. No arrests had been made, he said.
A Taliban spokesman, Abdul Latif Hakimi, who often claims responsibility for attacks on behalf of the Taliban, said by telephone from an undisclosed location he did not know if Taliban guerrillas had carried out the attack.
PHOTO CAPTION
Afghan policemen at the site of explosion in Kabul. (AFP/)