Angry crowds rally in Tunisia at funeral of shot opposition leader NEW: The casket bearing opposition leader Chokri Belaid enters the cemetery NEW: Protesters clash with security forces along the route of the funeral procession Military forces are deployed alongside police on the streets of the capital Belaid's widow and others say the government allowed a climate of political violence Tunis, Tunisia (CNN) -- Chanting loudly and waving flags, tens of thousands of people turned out Friday for the funeral of Tunisian opposition leader Chokri Belaid, whose assassination has sparked political uncertainty and violent protests. They followed his flag-draped casket through the streets of the capital, Tunis, to a cemetery where a sea of mourners waited shoulder-to-shoulder for him to be laid to rest. A phalanx of uniformed soldiers escorted the coffin bearers into the cemetery. Outside, protesters clashed intermittently with security forces that fired tear gas along the route, and a car could be seen burning in footage broadcast from the procession by a private TV channel. Many of those mourning Belaid are angry at the government, which they accuse of allowing a climate of political violence to spread unchecked. On the capital's central Habib Bourguiba Avenue, a flashpoint for protests, dozens of demonstrators fled as riot police fired tear gas. Sporadic clashes also flared on side streets. The military has been deployed alongside police to try to rein in the protests. READ: Tunisia gripped by political uncertainty after killing Belaid, a prominent secular politician, was shot dead as he left his home Wednesday morning to go to work, plunging the country into confusion. Weeping beside his casket Thursday, his widow, Besma Belaid, was among those pointing the finger at the climate fostered by the governing Ennahda party, led by moderate Islamists. It's an open invitation to violence. I can only accuse this party," she said. READ: Vocal critic of Islamist-led government gunned down in Tunisia Chokri Belaid had warned just this week that the government had given a green light to political violence. Ennahda denies any involvement in his death, the first political assassination since Tunisia's so-called Jasmine Revolution two years ago. The party's top officials are still trying to decide whether to accept their prime minister's decision Wednesday to sack his Cabinet and install a caretaker government until new elections are held. A general strike called by trades unions for Friday, the first such action in Tunisia in three decades, has closed many shops, cafes and other businesses. The national carrier, Tunisair, warned on its website of possible flight disruptions. On Thursday, young protesters threw rocks at security forces near the Interior Ministry. Police responded with tear gas, and officers riding double on motorcycles chased demonstrators. Other plainclothes police officers went door to door, looking for people who had been on the streets. When the protesters headed back to the streets, they were met by more tear gas. This game of cat-and-mouse lasted all day, but the protesters refused to leave. Protests have also rocked the central towns of Gafsa and Sidi Bouzid, the birthplace of the revolution that toppled former President Zine el Abidine Ben Ali two years ago. READ: Economic development key to consolidating democracy in Tunisia Some speculate that an extremist Salafist group may have been behind the assassination, but official investigators have yet to report back. Amna Guellali, of the rights group Human Rights Watch, said the government bears some responsibility because of its "laxity" in failing to respond to a climate of rising political violence. Many Tunisians are worried that the upheaval may lead to a return to the situation as it was before their country became the cradle of the Arab Spring revolution. As the questions and outrage over Belaid's death continue, many in the country will be observing a national day of mourning called Friday by union leaders. Dan Rivers reported from Tunis, and Laura Smith-Spark wrote and reported from London. CNN's Brian Walker contributed from Atlanta.