At least nine people have been killed in a suicide bombing outside the Afghan defence ministry in Kabul, officials have said.
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A police officer said all the dead were civilians and that "two or three" ministry personnel were among the injured in Saturday's blast.
Officials said an attacker riding a bicycle detonated explosives near the main entrance to the ministry.
"A suicide attacker has detonated himself within 30 metres of the defence ministry gate," Zahir Azimi, ministry spokesman, said.
Roads around the ministry building, which is near the presidential palace, were closed as emergency officials cleared the area of debris and washed blood from the street. A wall surrounding the ministry was pockmarked with shrapnel.
The Taliban claimed responsibility for the attack, which came as Chuck Hagel, the newly-named US secretary of defence, arrived in the Afghan capital.
"This was not a direct attack to target him [Hagel] but we want to send a message that we are always capable of hitting Kabul even when the top US defence official is there," Zabiullah Mujahid told the AFP news agency by telephone.
A spokesman for the International Security Assistance Force in Afghanistan, ISAF, said Hagel was safe.
Elsewhere in the country, at least nine people - eight of them civilians and one a policeman - were killed in a suicide bombing in Khost city.
The attack on the provincial capital of eastern Khost province came just after the Kabul blast.
"There was a joint Afghan and coalition forces patrol in this area. Suddenly a suicide bomber blew himself up and martyred eight Afghan teenagers from ten to 18-years-old and a policeman," said Sardar Mohammad Haya, chief of the Khost Police Quick Reaction Unit.
Hagel arrived in Kabul on Friday for his first trip abroad after being sworn in last month.
He was due to meet US commanders and Hamid Karzai, Afghan president.
Hagel said he would also make his own assessment about the United States' longest war as it enters its final stretch.
The visit comes after Karzai has taken steps to limit US military activities.
"I need to better understand what's going on," he said.
The visit is Hagel's first trip to Afghanistan since a mid-2008 visit with then-senator Barack Obama during Obama's campaign for the presidency.