KABUL - Up to seven people were injured Wednesday morning when an Afghan Defense Ministry bus came under attack in western capital city of Kabul, police said.

"A suicide bomber blew his explosive jacket up close to a bus carrying employees of defense ministry at about 7:10 am (local time) in Pul-e-Sokhta area in police district 3 in Kabul," the Kabul police said in a statement.  

The injured included six staff members of the ministry and a civilian passerby, the statement said, adding the injuries were not life-threatening.

Following the bombing, Taliban insurgent group claimed the responsibility.

Zabihullah Mujahid, a Taliban purported spokesman, told local media that a Taliban fighter named Sayed Jan targeted a bus of national army Wednesday morning, leaving over a dozen army personnel dead and injured.

"I heard that the suicide jackets wound not work in rainwater and snow but today it worked," a witness Mohammad Jafar told Xinhua.

"Shortly after the bus stopped for an employee to get on, I saw a man with an umbrella in his hand approaching the bus. Then I heard a big bang with a large flame under the bus," Jafar said.

The blast also damaged parts of the vehicle besides scattering the windowpanes of nearby shops and buildings.

"This morning's attack is not the first of its kind. More than eight army and police buses came under attack over the past five years in Kabul. The government has failed to end such bombings," he said.

Despite claims by the NATO-led force that the insurgency has been weakened, Kabul continued to be under regular attacks by the insurgent Taliban.

On Sunday, a suicide bomber was shot dead and his explosive- packed four-wheel drive car was safely defused in front of an office building of the country's High Peace Council in downtown Kabul.

The Taliban, who ruled the country before they were ousted by a US-led invasion in late 2001, renewed armed insurgency, staging ambush and suicide attacks, killing combatants as well as civilians.

Currently about 100,000 NATO-led forces, with nearly 66,000 of them Americans are deployed in the country to halt the Taliban attempt from returning to power.

The latest bombing attack underscores the challenges that Afghan army and police faced as they struggle to provide security across the country before assuming the full operational lead by spring this year and the departure of all US and NATO forces by the end of next year.

The Afghan forces have already took full control of areas where about 75 percent of the population lives.

Under US President Barack Obama's withdrawal plan, 33,000 US troops already pulled out of Afghanistan in September last year and another 34,000 will return home within one year.