On Friday, Omar Karami, an ally of Syria, said he was also protesting against what he saw as the appointment, rather than the election, of the legislature's new 128 members.
The elections are to start on 29 May.
Pro-Syrian politicians are facing an uphill struggle against powerful anti-Syrian factions that recently have joined together to end the pro-Syrian sway over the
"I have said a long time ago that a parliamentary seat will not affect [my] political career. Therefore, after a quiet and lengthy study, I have decided to boycott the election by not running in it or by voting," Karami said in an interview with Lebanese New-TV station.
Karami, who was the last prime minister to serve before Syria completed its troop withdrawal last month, said he had not previously thought of boycotting the elections but changed his mind "after seeing these farces and the extent of degradation to which political circles have reached, corruption at all levels along with lies and betrayal".
Karami's move followed similar decisions by former deputy prime minister Issam Faris and former legislator Tammam Salam who pulled out of the race, citing a divisive election law drawn up in 2000 at the height of Syria's control of Lebanon.
Karami said the boycott did not mean he was quitting politics. "We will remain in political life fighting for our principles and for serving the people," he said.
Omar Karami announced his
resignation in March
Karami is the political head of a prominent family from the northern city of Tripoli that has produced three prime ministers since Lebanon's independence from France in 1943.
He was forced to step down on 28 February under pressure from massive anti-Syrian demonstrations after the assassination of former prime minister Rafiq al-Hariri earlier in the month.
He was asked last month by President Emile Lahoud to return to form a new cabinet but gave up after several weeks without success.
The anti-Syrian opposition had accused Karami of stalling on the formation of a cabinet in the hope of postponing the elections, which it is confident it will win.
The elections begin on 29 May and take place on four consecutive Sundays. The country has been divided over the 2000 election law that demarcated large voting districts.
Pro-Syrian legislators, who currently command the majority in parliament, want the districts to be large, as that would favour them politically. The opposition favours small districts.
The poll will be the first after
Syria withdrew its troops
But after parliament failed to approve an election law that demarcates small voting districts, opposition leaders agreed to go along with the 2000 law.
There is widespread agreement among politicians that the 2000 law sets voting districts in a way that marginalises many Lebanese groups and boosts pro-Syrian candidates.
The influential Maronite Catholic Church has criticised
the law, saying it produces legislators who are not truly representative.
Nevertheless, some opposition groups went along with the government's decision to apply the same law in the elections - either because it suited their electoral interests or because they thought it could not be changed in time to hold elections on schedule as demanded by the international community.
The results are new divisions in the anti-Syrian camp, which had been united, both Christians and Muslims, following al-Hariri's assassination.
The opposition blamed the killing on Syria and its allied government in Beirut, a charge both denied. Mass anti-Syrian protests and international pressure led Syria to withdraw its army from Lebanon last month.
The elections, anxiously awaited by the United Nations and the United States, will be the first balloting free of Syrian forces, after nearly three decades of military and political dominance of Lebanon.