A suicide car bombing has taken place on the western edge of the Afghan capital Kabul, killing at least six people, Interior ministry sources said.

Interior Ministry sources said Saturday's blast killed six people, and injured 20 others, including one Afghan army officer, a policeman and four civilians.

Al Jazeera's Jane Ferguson, reporting from Kabul,said debris from the blast had been strewn over a large distance, and that several vehicles had been targeted.

The blast occurred at 3:00pm (10:30 GMT) on Saturday near a compound where Afghanistan's security agreement with the United States was to be debated by a Loya Jirga.

"The suicide attacker has detonated his explosive-packed car in an area packed with civilians," police chief Mohammad Zaher told AFP. "There have been casualties."

Afghan officials said that the bomber was targeting a vehicle carrying Afghan National Army (ANA) personnel.

About 3,000 elders are to meet next week for the Loya Jirga, a traditional meeting of elders, to debate the agreement, which would allow US troops to remain in Afghanistan after the final withdrawal of international combat troops at the end of 2014.

The explosion came just hours after President Hamid Karzai announced the final draft of the agreement had been completed, after lengthy negotiations between Afghan and US officials.

Karzai also said, however, that disagreements remain between the two countries over specific clauses of the agreement.

Source: Al Jazeera and agencies