Armed police escorted nine new Afghan lawmakers, who were awarded seats after a review of poll fraud allegations, into parliament, as the group they replaced and dozens of other lawmakers opposed to the change demonstrated outside.
Some members of parliament critical of the decision to oust fellow lawmakers after several months in the job threaten they will not take their seats again until the decision by the Independent Election Commission (IEC) is reversed.
If they do stay away it will further undermine an already weak institution at a worrying time for Afghanistan, with violence at record levels and the departure of most Western forces scheduled by the end of 2014.
"There is no law and democracy in Afghanistan, and foreigners who are here to support the government are here to support a dictator's government," said Mohammad Nahim Lalai Hamidzai, a lawmaker from Kandahar.
He described September 3 as "the funeral of law and democracy in Afghanistan" and said some 140 members of parliament had pledged to boycott the assembly. Parliament has a strength of 249 members.
In late August, the IEC said it would replace nine parliament deputies in line with a ruling by a court appointed by President Hamid Karzai. The court in June said that 62 lawmakers would have to vacate their seats and be replaced by new members because of alleged poll fraud.
The IEC softened its stance after initially rejecting the court decision as unconstitutional, a sentiment shared by many members of parliament, and international observers.
The bulk of the current parliament has vowed national protests over any changes, and last month some 3,000 people demonstrated outside the legislature.
"We don't have weapons and tanks, like the government," said Hajji Abdul Qadir, an ousted deputy from eastern Paktika Province.
"But with support from other lawmakers and supporters, we will demonstrate and take action very soon," he added.
Karzai has banned the ousted members of parliament from the building, said security official Fazlul Rahman.
"Police forces are ready and if someone wants to enter they will take action." Rahman said.
Karzai and the parliament have been at loggerheads since the election in September, which saw opponents of the president make major gains. Karzai has often been accused of treating parliament as a rubber stamp.