A suicide bomber in a car targeted two vehicles carrying foreign forces in the Afghan capital, Kabul, killing at least six Afghan civilians, officials have said.
It was not clear if any members of the foreign force were killed or wounded.
The Hezb-e-Islami insurgent group, allied with the Taliban, claimed responsibility for the attack.
A suicide bomber on a bicycle struck outside the Afghan Defense Ministry today in one of two attacks that claimed the lives of at least 18 people. Nine people were killed in the bombing at the ministry.
Around half an hour later, another suicide bomber attacked a police checkpoint in Khost, in eastern Afghanistan. An Afghan policeman and eight civilians died in the blast.
The Taliban says it was behind the attack at the ministry which coincided with a visit to the area by the US Defence Minister.
The Afghan Taliban has claimed responsibility for the suicide attack at an Afghan defence ministry gate in Kabul.
They said in a statement the attack "is a kind of message" for US defence secretary Chuck Hagel, who is visiting the country.
Hagel, who was in a safe location at an ISAF facility at the time of the blast, has planned to meet US commanders and troops and hold talks with President Hamid Karzai.
An Afghan defence ministry official told Reuters at least nine civilians had been killed and 14 people wounded in today's attack.
At least eight Afghan civilians have been killed in a suicide attack outside the defence ministry in Kabul, an Afghan official has told the Associated Press.
The Reuters news agency cited an official as saying at least nine people had died in the blast.
The explosion outside the Afghan defence ministry in Kabul has caused multiple casualties, Afghan officials have said.
A police spokesman said an apparent suicide attacker on a bicycle hit the main entrance to the building around 9:00am local time.
US defence officials have confirmed defence secretary Chuck Hagel, who is visiting the country, was in a safe location and unharmed.
He had been in a meeting at a coalition facility in the city at the time of the blast.
An explosion has occurred close to the Ministry of Defence in the Afghan capital Kabul, a department official has told Reuters.
Witnesses separately reported hearing a large blast to the news agency.
The incident comes a day after the US secretary of defence Chuck Hagel arrived in the country on a surprise visit.
Taliban suicide bombers have targeted a police building in the Afghan capital Kabul, sparking a gun battle with several other attackers. The raid started early this morning after a car bomb was set off at the gate of the traffic department in Kabul.
Police say another two or three attackers armed with suicide vests and weapons then entered the compound. It is the second raid inside Kabul in less than a week.
At least three suicide bombers have launched an attack on an Afghanistan government building in Kabul and a gun battle with security forces is ongoing, Afghan police told Reuters.
– ISAF statementA contractedcivilian employee of the International Security Assistance Force died afterbeing shot by a woman wearing an Afghan police uniform in Kabul, Afghanistantoday.
The incident iscurrently under investigation.
It is ISAF policy to defer casualtyidentification procedures to the relevant national authorities, and not discusscasualties or their conditions.