Lebanon’s squabbling politicians on Tuesday pushed the election of a new president back to the last day of the current incumbent’s term on Friday.

Parliament had been expected to meet on Wednesday but sharp disagreements led to a fourth postponement, amid increasing worries that political tensions could spill over into violence.

Michel Suleiman, Lebanon’s army commander, warned against the use of force in the political standoff. “Any weapon directed against the interior is a weapon of treachery,” he said in a message to his soldiers ahead of Lebanon’s 64th Independence Day later this week.

Army and police have reinforced their presence on the capital’s main arteries, around government buildings and near a luxury hotel on the waterfront where many members of the ruling anti-Syrian coalition have been holed up since September for fear of assassination.

The Fouad Siniora’s western-backed government and the opposition, which is led by the pro-Syrian and pro-Iranian Hizbollah movement, are unable to agree on a candidate to replace the pro-Syrian incumbent, Emile Lahoud.

Hizbollah has said it will not allow the choice of president to be imposed by the US. The government, meanwhile, accuses the opposition of serving the interests of Syria and Iran.

International mediators are attempting to bring the sides closer together but a compromise brokered by the Bernard Kouchner, French foreign minister, fell apart over the weekend. An angry Mr Kouchner threatened to expose the party responsible for blocking a solution.

If no agreement is reached by the Friday deadline, the president’s limited authority will fall to the government.

Both the opposition and the president have said that they will not allow this to happen, nor will they abide by the election of a president by the slim anti-Syrian majority in parliament.

They have threatened several forms of protests, including the seizure of government buildings. President Lahoud has hinted that he may set up a rival government before he leaves office.

Such steps could reignite clashes that broke out between government and opposition supporters in January, when several people were killed in two days of rioting.

The crisis focuses attention on the country’s Maronite Christian community from which, under Lebanon’s sectarian system, the president has to be chosen. But a list of candidates drawn up by the Maronite Patriarch with French encouragement has failed to produce a consensus.