According to the Reuters news agency, Hasan al-Senaid of the ruling Shi'ite Alliance bloc confirmed that three cafeteria workers had been detained and were being questioned about the blast.
No charges have so far been brought, however.
Today's session at parliament was convened to condemn the attack and got underway at about 12:20 local time (09:20 BST).
Many of the 275 MPs were not in attendance today as the house speaker Mahmud al-Mashhadani urged members to stay strong in the face of terrorist attacks.
"This meeting is a clear message to all terrorists and to everyone who tries to halt this blessed process, which we should sacrifice ourselves for," Mr al-Mashhadani said, according to the AFP news agency.
"You are capable of shouldering every difficulty."
A minute's silence was also held to remember the victims, which is thought to include two MPs among its number.
One has been identified as Mohammed Awad of the Sunni Muslim National Dialogue Front and the other is believed to be a member of the minority Kurdistan Islamic Union.
The blast itself was captured on Iraqi TV, which was conducting an interview at the time.
The footage depicts the chaos in the immediate aftermath of the explosion as lawmakers struggled in the darkness as dust and smoke filled the cafeteria.
US president George Bush last night condemned the attack and said it "reminds us … that there is an enemy willing to bomb innocent people in a symbol of democracy".
"It is in our interest to help this young democracy be in a position so it can sustain itself and govern itself and defend itself against these extremists and radicals," he added from the White House. "Our hearts go out to those who suffered as a result of this bombing.
"My message to the Iraqi government is: 'We stand with you as you take the steps necessary to not only reconcile politically, but also put a security force in place that is able to deal with these kinds of people.'"
Army General David Petraeus, the commander of the multinational forces in Iraq, called the blast an "attack on democracy by individuals who oppose the concept of government that is representative of and responsible to the people of Iraq".
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