Two people were killed and seven wounded when a mini-bus carrying workers from Afghanistan's Ministry of Education was hit by a bomb blast in the capital on Monday, the ministry said.

A roadside bomb blew up the bus while it was carrying workers to their offices in Kabul's eastern Bagrami district, the ministry said.

"The education ministry asks security forces to bring perpetrators to justice as soon as possible," it said in a statement.

Few other details were available and there was no claim of responsibility.

Government workers and members of the security forces are often targeted by insurgent groups, including the Taliban, who are seeking to topple the US-backed government in Kabul.

The Taliban have stepped up their insurgency since most foreign troops withdrew from Afghanistan at the end of 2014, although Kabul has enjoyed a period of relative calm during the harsh winter months.

That lull in violence was expected to end soon with the Taliban poised to launch their annual spring offensive.

Six people were killed by a suicide bomber on a motorcycle in Parwan district, northwest of Kabul, last week. On February 22, a Taliban suicide bomber killed 14 people and wounded 11 at a clinic in the same district.

Afghanistan's precarious security was underlined late on Saturday when at least two rockets hit the diplomatic zone in Kabul only hours after US Secretary of State John Kerry had held meetings with Afghan government leaders in the capital.

No injuries were reported.