BANGKOK — Thai troops clashed with die-hard protesters vowing to defend their fortified encampment in downtown Bangkok on Saturday following two days of running gunbattles that killed 16 people and wounded nearly 160.Scattered violence resumed Saturday morning, after encircling troops used tear gas, rubber bullets and live rounds on demonstrators on Friday and the protesters in turn set fire to tires and a police bus.The Red Shirt campaignThe Red Shirt protesters began their latest campaign to oust the government in March, saying it came to power illegitimately and is indifferent to the poor. In several rounds of violence since then, 43 people have been killed and more than 1,500 wounded, according to the government. The casualty toll included 16 killed and 157 wounded in the latest violence.Protesters have urged 82-year-old King Bhumibol Adulyadej to end his long silence and intervene, but there was no word from the widely revered ailing monarch.The latest violence erupted Thursday after the Red Shirts' military strategist — a former Thai general — was shot and seriously injured, apparently by a sharpshooter, as he spoke to foreign journalists.Witnesses saw several groups of a dozen or more people detained at the scene of several clashes. No figures were released on how many were detained.The Red Shirts, mostly rural poor, began camping in the capital March 12 to try to force out Prime Minister Abhisit Vejjajiva. They claim his coalition government came to power through manipulation of the courts and the backing of the powerful military.The military had forced Thaksin Shinawatra, the populist premier favored by the Red Shirts, from office in a 2006 coup. Two subsequent pro-Thaksin governments were disbanded by court rulings before Abhisit became prime minister.Explosions echoed overnight through streets emptied of shoppers and tourists, plumes of black smoke rose amid skyscrapers and hotels. The deteriorating security raised concerns that Thailand — a key US ally with Southeast Asia's second-largest economy — was teetering toward instability because of the two-month-long political crisis.In a message from New York, UN Secretary-General Ban Ki-moon appealed to both sides to "do all within their power to avoid further violence and loss of life."But with negotiations terminated, the situation appeared headed toward a final showdown on the streets."The situation right now is getting closer to civil war every minute," a protest leader, Jatuporn Prompan, said Saturday morning. "We have to fight on. The leaders shouldn't even think about retreat when our brothers are ready to fight on."