UPDATE 3-Islamists rally to defend Tunisian government after assassination
* Gun that killed Brahmi was used in earlier killing
* Hardline Salafist named as prime suspect
* Shops, banks closed and flights cancelled
* Protesters gather in central Tunis
(Releads with Islamist protest)
TUNIS, July 26 (Reuters) - Several thousand Islamists took to the streets of Tunis on Friday to defend the Islamist-led government from popular demands for it to resign over the assassination of a secular opposition politician.
As Islamists and secular opponents staged rival protests over the future of Tunisia's Ennahda government, the interior minister pointed the finger of suspicion at a hardline Islamist, saying the same gun had been used on Thursday as in a political killing earlier this year that provoked violent protests.
"The people want Ennahda again!" and "No to a coup against democracy!", the Islamist protesters chanted, rejecting demands for the government to make way for a national unity government.
Divisions between Islamists and their secular opponents have deepened since Tunisian President Zine al-Abidine Ben Ali was toppled in 2011 in the first of the Arab Spring revolutions.
In the second assassination of a secular politician in Tunisia this year, Mohamed Brahmi, a member of the Arab nationalist Popular Front party, was shot 14 times.
Thousands of anti-government protesters also massed in the capital on Friday, while shops and banks closed their doors and all flights in and out of the country were cancelled.
"Down with the rule of the Muslim Brotherhood," the secular protesters chanted, referring to the ruling Ennahda party, which draws inspiration from the Brotherhood, a pan-Arab Islamist movement.
Interior Minister Lotfi Ben Jeddou drew a direct link between the latest killing and the assassination of the Popular Front's leader Chokri Belaid on Feb. 6, which set off the worst violence in Tunisia since Ben Ali's downfall.
"The same 9mm automatic weapon that killed Belaid also killed Brahmi," he told a news conference, naming the main suspect as hardline Salafist Boubacar Hakim, already being sought on suspicion of smuggling weapons from Libya.
Authorities had identified 14 Salafists suspected of involvement in Belaid's assassination, and most were believed to be members of the local hardline Islamist group Ansar al-Sharia, he said.
Brahmi, 58, was a critic of the Ennahda-led ruling coalition and a member of the Constituent Assembly that has drafted a new constitution for the North African nation of 11 million.
German Chancellor Angela Merkel condemned what she called the "cowardly assassination" of Brahmi and demanded that his and Belaid's killers be swiftly brought to justice.
The Tunis stock exchange fell by 1.9 percent on Friday morning and the dinar currency was trading close to a record low against the euro.
Tunisia's political transition since the revolt that toppled Ben Ali has been relatively peaceful, with the moderate Islamist Ennahda party sharing power with smaller secular parties.
But the government has struggled to revive the economy and has come under fire from secularists who accuse it of failing to curb the activities of Salafi Islamists.
The Egyptian army's overthrow of Muslim Brotherhood President Mohamed Mursi on July 3 after mass protests against him has further energised the anti-Islamist opposition in Tunisia.
Brahmi's family said his funeral would take place on Saturday and he would be buried near the tomb of Belaid. Tunisian President Moncef Marzouki asked the army to organise a state funeral for Brahmi.
The government announced a day of national mourning on Friday, and radio stations broadcast patriotic songs.
Secularists called for the dissolution of the government and the formation of a national salvation administration, which was rejected by Prime Minister Ali Larayedh.
In Tunis late on Thursday, riot police fired tear gas in front of the interior ministry to disperse protesters. Similar demonstrations erupted in the cities of Sfax and Kef and in the southern town of Sidi Bouzid, the cradle of the Tunisian revolution, where protesters set fire to two Ennahda party offices.
Ben Ali's downfall unleashed unrest across the Arab world, unseating rulers in Egypt, Libya and Yemen, and leading to civil war in Syria.
Rached Ghannouchi, the Ennahda party leader, said the attack on Brahmi was aimed at "halting Tunisia's democratic process and killing the only successful model in the region, especially after the violence in Egypt, Syria and Libya".
"Tunisia will not follow the Egyptian scenario," he told Reuters. "We will hold on."
The assassination occurred as the country prepares to vote in the next few weeks on the new constitution before a presidential election later in the year.
The turmoil dealt another blow to efforts to revive Tunisia's vital tourism industry. Cultural events, including the Carthage Festival, were suspended following Brahmi's killing.
(Additional reporting by Fatma Matoussi; Writing by Giles Elgood and David Stamp)