Afghanistan's Speaker has led a walk-out of parliament, followed by nearly half the country's deputies.
Yunus Qanuni left the assembly because he said the government of President Hamid Karzai was ignoring parliament.
Many MPs want senior officials in Baghlan province to be suspended after a bombing there earlier this month.
Nearly 80 people were killed in the attack, including six MPs and about 60 children. The government has said it is still investigating the bombing.
Correspondents say much is still unclear about the bombing in Baghlan.
Some reports say many of the victims died from gunshot wounds and appear to have been shot by the MPs' bodyguards.