"We call on the justice minister to try Abd al-Halim Khaddam for grand treason and to take the necessary measures," Mahmud al-Abrash, the parliament speaker, said at the end of a televised session on Saturday.
Speaking from Paris, Khaddam on Friday launched an unprecedented attack on al-Assad, saying he had threatened Rafiq al-Hariri, the former Lebanese prime minister who was assassinated in February.
Khaddam, who moved to Paris after resigning in June, accused the government of making political blunders in Lebanon and of failing to deliver economic and political reforms at home, leaving millions of Syrians to go hungry.
Legislator Umeima Faddoul told the parliament session: "I ask the Syrian leadership to try him ... for humiliating 10 million Syrians when he said half of the Syrian people are eating from the garbage.
"I tell him, those who eat from the garbage are traitors like you... Treason is the darkest shade of black."
Khaddam told al-Arabiya television in an interview aired on Friday that al-Assad had threatened al-Hariri before he was assassinated.
Khaddam, a veteran aide to the president's father, the late Hafez al-Assad who ruled Syria for 30 years, would not speculate on who had ordered al-Hariri's murder, saying "we must wait" for the results of a UN inquiry that has already implicated senior Syrian officials.
Legislator after legislator stood up in parliament to accuse Khaddam of corruption and treason during four decades as a senior official in Syria. Some also accused him of betraying his country by moving to France.
"I ask the Syrian leadership to try him ... for humiliating 10 million Syrians when he said half of the Syrian people are eating from the garbage"
a Syrian legislator
"You don't deserve to be a Syrian," said a lawmaker, who did not give his name. "You can go to hell because no Syrian will forgive you, who hoped to return to your country one day on an American tank."
Syrian deputies are elected to parliament by popular vote but rarely diverge from the official line. They belong to a group of parties led by the ruling Baath party.
Another lawmaker said: "His comments last night constitute a criminal offence that reaches the level of treason and we demand he be put to trial before the Syrian security high court."
Khaddam's comments are likely to intensify international pressure on Damascus which has been mounting since the Beirut truck bombing that killed al-Hariri and 22 others.
Syria has denied involvement but pulled its troops out of Lebanon in April after a 29-year military presence.