Prime Minister Fouad Siniora said the killers of MP Antoine Ghanim would not be allowed to succeed in their aims.
MPs are due to choose a new president next week. The killings of several anti-Syrian figures have left
Banks, schools and government offices have been closed in
The education ministry said schools and universities would remain closed again on Friday, when a funeral would be held.
Mr Ghanim died with at least six others in a car bombing in the mainly Christian Sin al-Fil district on Wednesday.
Mr Siniora said on Thursday: "The hand of terror will not win and will not succeed in subduing us and silencing us.
"The Lebanese will not retreat and will have a new president elected by lawmakers, no matter how big the conspiracy was."
He has called for a UN investigation into the assassination of Mr Ghanim, who had returned to
The country has been mired in an ongoing political crisis, with a deadlock between pro- and anti-Syrian factions in parliament.
'Hand of terror'
But some Lebanese politicians were quick to blame
Saad Hariri, son of Rafik Hariri, a former prime minister who was assassinated in a bomb attack in 2005, said responsibility lay with the "cowardly regime" of
Even pro-Syrian Mr Lahoud said it was no coincidence someone was killed whenever there were positive developments in
US President George W Bush denounced the "horrific assassination", which he described as attempts by
The attack has also been criticized by the
Six other leading figures in
PHOTO CAPTION
Antoine Ghanim