* Shops, banks closed and flights cancelled
* Country braces for more street violence
* Brahmi's killing is second such assassination
By Tarek Amara
TUNIS, July 26 (Reuters) - Shops and banks in Tunisia wereclosed and all flights cancelled on Friday as the country bracedfor more street violence a day after the assassination of anopposition politician.
Mohamed Brahmi was shot dead on Thursday in the second suchpolitical killing this year, which prompted violent protestsagainst the Islamist-led government in the capital and othercities and a strike call by the main trade union body.
Tunisians were prepared for another difficult day after thesecular opposition called for street rallies to topple thegovernment led by the Islamist Ennahda Party. Islamists calledfor a demonstration after Friday prayers.
Brahmi belonged to the secular, Arab nationalist PopularFront party, whose then-leader, Chokri Belaid, was shot dead onFebruary 6. Belaid's killing set off the worst violence inTunisia since President Zine al-Abidine Ben Ali fell in 2011 inthe first of the Arab Spring revolutions.
Brahmi, 58, was a critic of the Ennahda-led ruling coalitionand a member of the Constituent Assembly that has drafted a newconstitution for the North African nation of 11 million.
Shops and banks were shuttered in anticipation of violenceon Friday. All flights were cancelled because of a strike calledby the main labour organisation, the civil aviation office said.
Divisions between Islamists and their secular opponents havedeepened since the popular uprising against Ben Ali, whichunleashed unrest across the Arab world, unseating rulers inEgypt, Libya and Yemen, and leading to civil war in Syria.
Brahmi's family said his funeral would take place onSaturday and he would be buried near the tomb of Belaid.
Secularist called for the dissolution of the government andthe formation of a national salvation administration, which wasrejected by Prime Minister Ali Larayedh.
In Tunis late on Thursday, riot police fired tear gas infront of the Interior Ministry to disperse protesters, a Reuterswitness said.
CRADLE OF REVOLUTION
Similar demonstrations erupted in the cities of Sfax and Kefand in the southern town of Sidi Bouzid, the cradle of theTunisian revolution, where protesters set fire to two Ennahdaparty offices.
Tunisia announced a day of national mourning on Friday and radio stations broadcast patriotic songs.
The interior minister is scheduled give details of Brahmi'skilling at a news conference later on Friday.
Tunisia's political transition since the revolt that toppledBen Ali has been relatively peaceful, with the moderate IslamistEnnahda party sharing power with smaller secular parties.
But the government has struggled to revive the economy andhas come under fire from secularists who accuse it of failing tocurb the activities of Salafi Islamists.
The Egyptian army's overthrow of Islamist President MohamedMursi on July 3 following mass protests against him has furtherenergised the anti-Islamist opposition in Tunisia.
Rached Ghannouchi, the Ennahda party leader, said the attackon Brahmi was aimed at "halting Tunisia's democratic process andkilling the only successful model in the region, especiallyafter the violence in Egypt, Syria and Libya".
"Tunisia will not follow the Egyptian scenario," he toldReuters. "We will hold on."
After the killing of Brahmi, who had applauded the Egyptianarmy's removal of Mursi, the leader of his Popular Front calledfor non-violent action to oust the Tunisian government.
The assassination occurred on Tunisia's Republic Day as thecountry prepares to vote in the next few weeks on the newconstitution before a presidential election later in the year.
The turmoil dealt another blow to efforts to reviveTunisia's vital tourism industry. Cultural events, including theCarthage Festival, were suspended following Brahmi's killing.
Secular President Moncef Marzouki appealed for calm anddialogue, but Tunisia looked set for further instability. (Additional reporting by Fatma Matoussi; Editing by GilesElgood)