Shocked Tunisians faced calls Thursday for a united front against extremism after an attack on foreign tourists that left 19 people dead and bore the hallmarks of a jihadist assault.

The main trade union confederation and other civil society groups announced plans for a silent demonstration outside the Tunis museum where 17 foreign tourists and two Tunisians were killed on Wednesday.

France condemned Wednesday a bloody armed attack on a museum in the Tunisian capital in which 17 tourists from Poland, Italy, Germany and Spain were killed.

"I condemn this terrorist attack in the strongest terms. There has been a hostage-taking, without doubt tourists have been affected, killed," French Prime Minister Manuel Valls said in Brussels after talks with European Commission President Jean-Claude Juncker.

A popular Tunisian comedian, a television host and a colleague went on trial Wednesday in a case in which one them allegedly impersonated the president in a telephone conversation with a businessman.

Defense attorney Mounir Ben Salha asked the court to dismiss the case and to free satirist Migalo, whose real name is Wassim Lahrissi, television host Moez Ben Gharbia and Abdelhak Toumi.

Gunmen stormed Tunisia's national museum killing 17 foreign tourists and two Tunisians Wednesday in an attack that raised fears for a rare success story of the Arab Spring.

The brazen daytime assault sparked panic at the nearby parliament and the National Bardo Museum, an iconic attraction in a country whose economy depends greatly on tourism.

Canada denied asylum Monday to the brother-in-law of deposed Tunisian dictator Zine El Abidine Ben Ali, saying he had likely used his position to commit "serious" crimes.

The Immigration and Refugee Board said in hearing documents that it believes Belhassen Trabelsi has "committed serious non-political crimes," which would make him ineligible for refugee protection.

The Tunisian prosecution on Monday refused to release a popular comedian and a television host detained for allegedly offending the president, a spokesman said.

Sofiene Sliti said the court turned down a request by the lawyers of satirist Migalo, whose real name is Wassim Lahrisi, and television host Moez Ben Gharbia for their release.

Tunisian authorities arrested a popular comedian and a television show host Friday for offending President Beji Caid Essebsi, whose office promptly denied it had anything to do with the case.

"The prosecutor has decided to place in detention" satirist Migalo, whose real name is Wassim Lahrissi, and television host Moez Ben Gharbia, prosecutor's office spokesman Sofiene Sliti said.

Tunisia's judges went on strike Thursday to protest a proposed legislative change they claim would undermine the independence of the judiciary by allowing the government to appoint members of their supervisory body.

"All judges participated in the strike," said Raudha Karafi, president of the Association of Tunisian Magistrates.

Tunisian security forces on Monday uncovered a second arms cache in three days near the border with Libya, the interior ministry said.

"As part of ongoing operations against terrorist cells and their members... (security forces) have discovered a new weapons cache 15 kilometers (nine miles) from Ben Guerdane" in the southeast, it said.

The Tunisian military rescued 86 African migrants at sea off the town of Zarzis aboard a makeshift boat bound for the Italian island of Lampedusa, an official said Wednesday.

The group were fleeing the conflict in neighboring Libya, from the port of Zuwarah about 60 kilometers (35 miles) from Tunisia, when their vessel started taking water on Tuesday afternoon, the Tunisian coastguard official said.