"This government will stay in office," Tunisian Prime Minister Ali Larayedh told state television yesterday.
"We are not clinging to power, but we have a duty and a responsibility that we will exercise to the end," he added, proposing December 17 for a general election.
An official declaration of mourning came after the discovery yesterday of soldiers' bodies in the Mount Chaambi area, near the border with Algeria. Troops there have been hunting Al-Qaeda-linked fighters.
State television ran pictures of the mutilated corpses of the victims.
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In a televised address, President Moncef Marzouki, a secular politician allied to the ruling moderate Islamic Ennahda party, called for national unity after the soldiers' deaths.
"If we want to face up to this danger we have to face up to it united," he said.
"I call on the political class to return to dialogue because the country, society, is under threat," he added.
The government has blamed his murder on Islamist extremists and Marzouki regretted that this "tragedy" had divided the country rather than uniting it.
But the government's critics say the Ennahda-led cabinet has failed to rein in radical Islamists who have grown in influence and stand accused of a wave of attacks since the 2011 uprising.
Since Brahmi's death, around 60 politicians have pulled out of the work of the National Constituent Assembly (NCA) that is drawing up the country's new constitution.