The NATO-led international force in Afghanistan said on Friday suspects had been rounded up in connection with a suicide bombing near the German embassy in Kabul that killed five people.
Afghan security forces supported by foreign troops detained "senior insurgents" responsible for the bombing near the embassy on 17 January during overnight raids, said the International Security Assistance Force (ISAF).
The "insurgent commanders associated" with the attack were detained in Logar province and Kabul, ISAF said in a statement without mentioning the number of suspects arrested.
A "senior insurgent commander" was killed and a "facilitator" of makeshift bomb attacks also arrested, it added.
Five people were killed -- four civilians and a US soldier -- when the bomb exploded opposite the German embassy and near the largest US military camp in Kabul in what was the first suicide blast to rock the Afghan capital this year.
The Taliban, who were ousted from power by the 2001 US-led invasion of Afghanistan and are waging a deadly insurgency, claimed responsibility.
There are nearly 70,000 foreign troops under NATO and US command in Afghanistan fighting a Taliban insurgency alongside Afghan forces.
A video made public by the US centre for surveillance of Islamist sites last Sunday showed a presumed member of Al-Qaeda threaten Germany with reprisals for its presence in Afghanistan.
Germany has about 3,300 soldiers in the relatively safe north of Afghanistan as part of the NATO-led ISAF.