Lebanese President Michel Sleiman said on Saturday he had lodged an appeal with the Constitutional Council challenging parliament's decision to extend its mandate and delay elections.
In a televised speech, Sleiman said he had asked the council to rule "neutrally and as quickly as possible" whether the move was constitutional.
On Friday, parliament voted unanimously to extend its mandate by 17 months to November 2014 from this month, after failing to adopt a new electoral law at a time of deep divisions over the war in neighbouring Syria.
The motion was submitted by independent Christian MP Nicolas Fattouche, but almost all parliamentary groups supported it.
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The text of the motion to extend the normal four-year term said it was due to "the security situation in several Lebanese regions that gives rise to political escalation and division which often take on confessional forms."
Lebanon is officially neutral in the conflict in Syria, but the fighting has aggravated tensions among its many religious and ethnic communities.
The powerful Shiite Muslim party Hezbollah and its allies have backed the regime of President Bashar al-Assad in its efforts to crush the uprising that began in March 2011.
But opposition parties largely support the Sunni-led rebellion against the Syrian regime.
Hezbollah fighters are in Syria, backing government forces, and several Lebanese Sunni clerics have urged members of their community to join the conflict on the side of the rebels.