At least six people were killed in a suicide car bombing near a compound in Kabul where a security pact between Afghanistan and the U.S. is to be debated.
Afghan officials say at least one soldier died in Saturday's blast, and that 22 people were wounded. Civilians were among the casualties.
There was no immediate claim of responsibility for the attack, which targeted an Afghan army vehicle.
Thousands of Afghan political and tribal leaders are set to begin meeting Thursday to discuss a security agreement with the United States. The agreement would let U.S. troops stay in Afghanistan after the final withdrawal of international combat troops at the end of 2014.
Earlier Saturday, Afghan President Hamid Karzai urged the Taliban to lay down its weapons and participate in the meeting. The Taliban has been reluctant to take part in the gathering.
Afghan and U.S. officials have been seeking to iron out a bilateral security pact that will help determine how many U.S. troops and bases remain in Afghanistan after 2014.