TBLISI, GEORGIA — WEARING a headband and clutching a club, Georgi Natroshvili stood guard early yesterday at the city's television center - headquarters of the movement to oust Georgian President Zviad Gamsakhurdia - saying he feared violence but was ready to fight.After several weeks of rising tension, contending political forces clashed in the streets of this capital city over the weekend, and participants fear bloodshed in coming days. "Civil war is inevitable here in Georgia," said Mr. Natrosvili, a translator. "The proportion of the forces of both sides is about even, and there is no way to reconcile positions." The Georgian crisis is widely viewed as a test of democracy in the republics breaking away from the Soviet Union. It is being carefully watched as a portent of new forms of human rights violations and suppression of the rights of ethnic minorities as the Soviet Union breaks apart. Over the weekend, Russian President Boris Yeltsin and Kazakhstan President Nursultan Nazarbayev were trying to mediate another potential hot spot, the near-war between neighboring Caucasus republics Azerbaijan and Armenia. President Gamsakhurdia is at the center of the Georgian storm, after being elected in a landslide vote last spring. Since taking office, he has alienated many Georgians, who say he has assumed the same trappings as the Communists he helped oust from power. They charge he is gathering absolute power, while failing to keep his promise to implement democratic reforms. Though virtually all the political forces in Georgia support independence from the Soviet Union, many now worry that they could be trading on e form of dictatorship for another. Gamsakhurdia has denounced his critics as "putschists" bent on seizing power from a democractically elected president. "They are practically illegal," says Nodar Gabashvili, deputy foreign minister. "They refuse to recognize the Constitution and the decisions of Parliament." In past months, Gamsakhurdia has responded to criticism from opposition party members and Western journalists and politicians with increasingly shrill claims that they are "agents of the Kremlin." Since the failed hard-line coup in Moscow last month, Gamsakhurdia has added a new twist. He claims opponents are taking orders from democratic movement leader and former Foreign Minister Eduard Shevardnadze, who served for many years as head of the Georgian Communist Party. For the last three weeks, the city has been paralyzed by growing political agitation. Both sides have assumed a siege mentality and engaged in daily protests at opposite ends of Rustaveli Prospect, the city's main thoroughfare. The protests gained momentum after a Sept. 2 incident in which Georgian national guardsmen fired shots to disperse an opposition demonstration, wounding at least three people. "Everyone who disagrees with him or is neutral to his political course automatically becomes his personal enemy," said Irina Sarishvili, spokesman for the National Democratic Party (NDP), which calls for Gamsakhurdia's ouster. Early yesterday, tension here reached new heights, threatening to engulf the mountainous republic in what nearly everyone predicts will be a bloody conflict. About 10,000 Gamsakhurdia supporters, screaming "Zviad, Zviad" and "Georgia, Georgia" marched down Rustaveli Prospect on the headquarters of the National Independence Party (NIP), another opposition group. Party members manned barricades in front of the headquarters to block the path of the presidential supporters. At the barrier, the two sides exchanged heated verbal threats, some flinging sticks menacingly at opponents. Over a loudspeaker, Irakli Tseretelli, NIP leader, made last-ditch appeals for calm, but the calls weren't heeded. Chaos quickly ensued as the several hundred opposition loyalists resorted to rock-throwing and produced a fire hose to beat back the Gamsakhurdia forces. Several tear-gas canisters also fell into the crowd, but that didn't hold off the president's supporters for long. Soon the opposition was in full flight and the pro-Gamsakhurdia crowd descended on the headquarters, smashing all windows on the first floor. NIP supporters found inside were roughed up then hustled off in ambulances. The clash in the early hours of yesterday capped a day of battles that began Saturday. A small group of about 50 NDP members led by Ms. Sarishvili staged a sit-in in front of the Parliament building, saying they would maintain a hunger strike until NDP leader Georgi Chanturia was released from prison. He was arrested last Monday on his way to meet with US Embassy officials in Moscow and to hold a news conference there. Government officials denied the arrest was political, saying Chanturia was being charg ed with disturbing the peace for calling for the erection of the barricades in front of opposition party offices. Several thousand enraged Gamsakhurdia loyalists, keeping vigil outside the Parliament, moved to disperse the small protest, despite militia efforts to keep the peace. Democratic party members fought their way through the crowd as punches were thrown. Sarishvili and several others were hospitalized. Gamsakhurdia, claiming that Parliament was under attack and a coup attempt was in progress, issued a call on republican television for all Georgians to come and defend the Parliament. Later, the opposition seized the TV station. By Saturday evening, thousands had responded, and yesterday more joined their ranks. Following the incident at parliament, the broad-based opposition movement held a spontaneous rally of about 25,000 people. Former Prime Minister Tengiz Sigua, ousted several weeks ago by the Georgian president, called for the crowd to march on Parliament and demand the implementation of democratic reforms and the president's resignation. Attempts to organize talks between the two leaders quickly broke down. So far, no shots have been fired. But the loyalties of the republic's heavily armed national guard are divided. The guards' commander, Tengiz Kitovani, says the force will try to remain above the political fray. But he has said on earlier occasions that if the opposition is attacked, he and a majority of his troops will intervene on their behalf.