A security forces special unit has been deployed and part of the 220-kilometre (140-mile) Algerian border closed, with "strict checks" being carried out at the nearby Bou Chekba crossing point, the source added.
Five people are wanted in connection with the attack, on Monday, in which the head of the police station in the western region of Kasserine, Anis Jlassi, was shot and killed and four of his men wounded.
"The security forces continue to scour the sealed-off area to catch the members of this armed group," the spokesman for Interior Minister Khaled Tarrouche said late on Monday.
Tarrouche did not specify the number, origin or membership of the group behind the attack.
But local sources say it was carried out by four "bearded men" spotted by a guard at an oil company near Bou Chebka, two kilometres (1.2 miles) from the Algerian border.
Jlassi, the 27-year-old slain policemen, was due to be buried in his central home town of Chebika on Tuesday.
Clashes, strikes and attacks by hardline Islamists have multiplied across Tunisia in the run up to the second anniversary of the start of Tunisia's revolution, which will be marked next Monday.
Members of Tunisia's militant Salafist movement, thought to number between 3,000 and 10,000, have been implicated in numerous acts of violence since last year's revolt.
In an interview published on Friday, President Moncef Marzouki expressed concern over weapons falling into the hands of Islamists across North Africa since the fall of Libyan dictator Moamer Kadhafi.
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Five people are wanted in connection with the attack, on Monday, in which the head of the police station in the western region of Kasserine, Anis Jlassi, was shot and killed and four of his men wounded.
"The security forces continue to scour the sealed-off area to catch the members of this armed group," the spokesman for Interior Minister Khaled Tarrouche said late on Monday.
Tarrouche did not specify the number, origin or membership of the group behind the attack.
But local sources say it was carried out by four "bearded men" spotted by a guard at an oil company near Bou Chebka, two kilometres (1.2 miles) from the Algerian border.
Jlassi, the 27-year-old slain policemen, was due to be buried in his central home town of Chebika on Tuesday.
Clashes, strikes and attacks by hardline Islamists have multiplied across Tunisia in the run up to the second anniversary of the start of Tunisia's revolution, which will be marked next Monday.
Members of Tunisia's militant Salafist movement, thought to number between 3,000 and 10,000, have been implicated in numerous acts of violence since last year's revolt.
In an interview published on Friday, President Moncef Marzouki expressed concern over weapons falling into the hands of Islamists across North Africa since the fall of Libyan dictator Moamer Kadhafi.
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