Kabul police chief escapes suicide blast in his office

 A suicide bomber walked into the offices of the Kabul police chief on Sunday and detonated his explosives, killing a senior aide in an attack that highlighted poor security in the Afghan capital.
Kabul police chief Zahir Zahir told AFP that the attacker had evaded checkpoints at the force's heavily-guarded headquarters by wearing a police uniform.
"I'm fine, but one of my best officers, my chief of staff Yassin Khan, was killed and six were wounded," Zahir said, speaking just an hour after surviving the apparent assassination attempt.
"It was a suicide bomber with police uniform on. As he was stopped trying to enter my room, he detonated his explosives.
"We are investigating how he entered the police headquarters."
The Taliban claimed responsibility for the attack.
"This morning at around 9:00 am, a martyrdom attack was carried out against the enemy which killed a lot of them," Zabiullah Mujahid, a Taliban spokesman, said on his Twitter account.
"The attack was carried out... inside Kabul police HQ while foreign advisers and police were meeting."
There were no reports of foreign casualties, and the Taliban often exaggerate death tolls after attacks.
Kabul is regularly hit by Taliban bombings, with the military, police and government officials among those targeted despite heightened security with multiple checkpoints, blast walls and armed guards.
- NATO troops exit -
Another Taliban bomb exploded earlier on Sunday in Kabul, causing no casualties.
In the last major blast in the capital, four Afghan soldiers were killed and around a dozen people wounded when a roadside bomb planted by the insurgents exploded on October 21.
That blast was a remote-controlled bomb targeting an Afghan army bus.
Afghan soldiers and police have taken on the lead role in thwarting the Taliban, but national stability could be at risk as US-led NATO troops pull out.
This year alone more than 4,600 Afghan soldiers and police have been killed in fighting, according to recent US figures.
The NATO troops end their 13-year combat mission in Afghanistan next month, with about 12,500 soldiers due to stay on into next year on a new training and support mission.
President Ashraf Ghani, who came to power in September, has said that Afghan forces are ready to impose security.
This summer the Taliban launched several offensives during a prolonged political deadlock in Kabul as Ghani and his rival Abdullah Abdullah both claimed to have won the fraud-mired presidential election.
The two men eventually signed a power-sharing agreement, with Abdullah appointed to the new position of "chief executive".
Efforts to start peace talks with the Taliban collapsed acrimoniously last year, though the new administration may make fresh moves to open negotiations and bring the war to an end.
Ghani used his inauguration speech in late September to call for insurgents to join peace talks.
"Any problems that they have, they should tell us, we will find a solution," he said.
NATO troop numbers peaked at 130,000 in 2010, but now stand at less than 34,000.