Defiant Thai opposition protesters stormed the army headquarters and besieged Prime Minister Yingluck Shinawatra's party offices on Friday, intensifying their fight to bring down her government. An anti-government protester holds a picture of the Thai Royal family at the army headquarters during a protest in Bangkok. (AFP/Nicolas Asfouri) Boisterous demonstrators have targeted key government buildings in Bangkok in the biggest street protests since mass rallies in 2010 degenerated into the kingdom's worst civil strife in decades. The protesters -- a mix of royalists, southerners and the urban middle class, sometimes numbering in their tens of thousands -- are united by their loathing of former premier Thaksin Shinawatra. The controversial former telecoms tycoon was ousted in a military coup in 2006 and lives in self-imposed exile, but he is widely believed to be the real power behind the embattled government of his younger sister Yingluck. Protesters are demanding the end of the "Thaksin regime" and want to replace the government with an unelected "people's council". "The basic desire of the protesters and the protest leaders is to create chaos and destruction, presumably hoping that the military will have to intervene and take power from the government," said Thailand expert Andrew Walker, a professor at Australian National University. In the latest provocative move targeting a symbol of state power, demonstrators forced open the gates of the compound of the army headquarters in Bangkok and occupied the lawn inside for several hours, calling on the military to support their fight to bring down the government. "We want to know whether the army will stand by the people or a dictator," said a protest leader, Amorn Amornrattananont. In a statement released hours later, army chief Prayuth Chan-O-Cha urged protesters to respect "the democratic process under the law". "Please do not try to make the army take sides," he said, urging people to come together ahead of revered King Bhumibol Adulyadej's birthday on December 5. "The army does not want any side to bring the monarchy into any political conflicts," he added. The generals are traditionally seen as staunch defenders of the monarchy with close links to its supporters in the royalist "Yellow Shirt" protest movement -- the arch-rivals of the pro-Thaksin "Red Shirts". But many experts believe the army does not want to become involved in the latest standoff -- either in support of, or against, the government -- for fear of a repeat of the 2010 bloodshed. The military's ties with the now-inactive Yellow Shirts also appear to have frayed, while the country is quietly bracing for the eventual end of ailing King Bhumibol's more than six-decade reign. PM's plea for calm falls on deaf ears Yingluck has ruled out using force against the demonstrators, who also massed Friday outside the headquarters of Yingluck's Puea Thai party, setting up a tense standoff with riot police for several hours before protesters dispersed of their own accord. With their spirits buoyed by free food and a party atmosphere, demonstrators have massed at several locations around the capital, occupying the finance ministry and blockading several others. Their numbers have fallen sharply since an estimated crowd of up to 180,000 people joined an opposition rally on Sunday. But turnout is expected to spike again over the weekend as organisers seek a final push ahead of celebrations for the king's birthday on December 5, which is traditionally marked in an atmosphere of calm and respect. Rally leader Suthep Thaugsuban called on supporters to besiege more important buildings over the weekend including two state-owned telecoms firms and even Bangkok's zoo, and to tighten their blockade of government ministries. He also urged people to gather near the heavily guarded Government House on Sunday. "December 1 will be our day of victory," he said. "People might ask, 'Is invading government places illegal?' Then you have to smile at them and say 'My dear if it is not against the law at all, then we cannot win'," Suthep said. The protests snowballed after the ruling party tried to introduce an amnesty that could have allowed Thaksin's return from self-imposed exile, and have continued despite the Senate's rejection of the bill. He remains a hugely divisive figure seven years after he was deposed by royalist generals. Pro-Thaksin parties have won every election for more than a decade but Yingluck has given no indication that she is thinking of calling fresh polls as a way out of the crisis. Thaksin is adored by many of the country's rural and urban working class but hated by many southerners, middle-class Thais and the Bangkok elite, who see him as corrupt and a threat to the monarchy. - AFP/ec