Unrest in Thailand intruded for the second straight year on a summit of Southeast Asian leaders as the Thai prime minister was forced to abandon his trip at the last minute Thursday amid fears of violence. 
 
 One day after declaring a national state of emergency, Prime Minister Abhisit Vejjajiva announced he would skip the 16th annual summit of the Association of Southeast Asian Nations in Vietnam to deal with thousands of "Red Shirt" anti-government protesters who have paralyzed parts of the Thai capital. 
 
 The tensions seized the attention of ASEAN leaders, who pride themselves on keeping one another's political affairs out of the limelight. 
 
 "The situation in Bangkok is worrying, and it's a somber backdrop to our discussions," Singaporean Foreign Minister George Yeo said at the summit's opening. "I really hope that the situation there will not lead to violence." 
 
 The Thai upheaval even upstaged concerns about Myanmar's upcoming elections, which have been boycotted by the main opposition party because its leader has been forbidden from participating. 
 
 Myanmar's junta plans to call elections sometime this year, but under the election laws, detained pro-democracy leader Aung San Suu Kyi is forbidden from participating. 
 
 Last week, members of her party, the National League for Democracy, announced they would not participate in the polls, the first in 20 years. 
 
 "It's disappointing that, because of the way the election laws have been crafted, it's not possible for the NLD to participate in the elections," Yeo said, speaking to reporters on the sidelines of the meeting Thursday morning. 
 
 However, he said, it was unlikely that the group would strongly criticize Myanmar's junta. 
 
 "We are not in a position to punish Myanmar," Yeo said. "If China and India remain engaged with Myanmar, then we have to." 
 
 Leaders from the 10 ASEAN nations had planned to focus on economics, where member countries with widely diverging political systems _ ranging from democracies to communism to a military junta _ share more common ground. 
 
 ASEAN hopes to advance its goals of forming a European-style economic community by 2015 and promoting development across the region. 
 
 Last year's summit was hijacked by the same protesters, forcing some visiting leaders to be airlifted out by helicopter. The Red Shirts, who briefly raided Parliament on Wednesday, are calling for Abhisit to dissolve Parliament within 15 days and call new elections. Instead, the prime minister has offered to do so by the end of the year. The Red Shirts claim he took office illegitimately in December 2008 with the help of military pressure on parliament. 
 
 The confrontation is part of the long-running battle between partisans of former leader Thaksin Shinawatra, ousted by a 2006 military coup, and those who oppose him. Thaksin was accused of corruption and showing disrespect to the country's revered monarch. 
 
 The demonstrators benefited from Thaksin's populist policies such as cheap health care and village loans. 
 
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 Associated Press writers Margie Mason and Tran Van Minh in Hanoi contributed to this report. ||||| Bangkok, Thailand (CNN) -- Thailand's Prime Minister Abhisit Vejjajiva declared a state of emergency Wednesday, hours after anti-government demonstrators stormed the country's parliament. 
 
 Speaking on nationwide television, he said the "purpose is to restore peace and order and to stop the spreading of false information to the Thai public." 
 
 Vejjajiva said the measure is effective in Bangkok and nearby provinces and "will limit certain rights of people." 
 
 According to the order, Deputy Prime Minister Suthep Thuagsuban has been appointed to administer the emergency law. 
 
 While the prime minister stressed that the measure is not mean to disperse people, the decree bans the gathering of more than five persons who are deemed to instigate an emergency situation. 
 
 It bans the publishing, broadcasting or spreading information considered a threat to national security and it prohibits people from staying in certain areas. 
 
 Thai iReporters share their images 
 
 The emergency allows authorities to take actions without court orders, such as summoning people, arresting and detaining people, and embarking on searches. 
 
 It allows authorities access to any communications, such as fax or telephone and gives them the power to end communications. Authorities are also permitted to stop Thai citizens from leaving the country. 
 
 Demonstrators Wednesday had been keeping a promise to intensify protests unless Vejjajiva dissolves parliament. 
 
 Explainer: What are the protests about? 
 
 The state of emergency was declared a few hours after the protesters stormed into the parliament building and then dispersed to regroup at their main gathering places at Phan Fa Bridge and Rajaprasong Intersection. 
 
 Lawmakers who were inside the parliament building as the protesters began arriving made a quick exit, some climbing over fences. 
 
 A helicopter was dispatched to pick up Deputy Prime Minister Suthep Thuangsuban and some other officials, Abhisit's office said. 
 
 iReport: Scene from Wednesday demonstration 
 
 The cabinet met to extend the country's Internal Security Act for another two weeks to help maintain order in the capital as the protests show no signs of abating. 
 
 The act has been in effect since March 11, two days before the protesters began their mass demonstrations in Bangkok. 
 
 On Tuesday, Abhisit spoke on television saying the rallies violated the constitution. 
 
 The demonstrators have disregarded all calls to disperse from Bangkok's commercial hub. The nation's tourism minister, Chumpol Silapaarcha, has said the protests could affect tourism by about 10 percent. 
 
 The group, United Front for Democracy Against Dictatorship, is made up of supporters of former Prime Minister Thaksin Shinawatra, who was ousted in a bloodless military coup in 2006. 
 
 He fled the country in 2008 while facing trial on corruption charges that he says were politically motivated. He remains hugely popular. 
 
 The protesters say Abhisit was not democratically elected and have demanded that he call elections.
– Thailand's prime minister has canceled an appearance at the annual Southeast Asia summit as rioters threaten to topple his government. Abhisit Vejjajiva declared a state of emergency yesterday hours after anti-government protesters stormed the country's parliament in Bangkok. The decree bans spreading information that threatens national security and allows authorities to arrest, detain and search people without court order, CNN notes. "The situation in Bangkok is worrying, and it's a somber backdrop to our discussions," Singaporean Foreign Minister George Yeo said as the summit opened today in Vietnam. Last year's summit was hijacked by the same red-shirted Thai protesters, forcing some visiting leaders to be airlifted out by helicopter, notes AP. Protesters have vowed not to disperse until Vejjajiva dissolves parliament. The group, known as the United Front for Democracy Against Dictatorship, supports former Prime Minister Thaksin Shinawatra.