BENGHAZI – Libya on Sunday celebrated two years since the start of the revolt that toppled Muammar Gaddafi, with security forces on high alert amid fears of a fresh violence that have plagued the north African nation.The anniversary of the uprising that ended with Gaddafi’s killing in October 2011 comes as Libya’s new rulers battle critics calling for a "new revolution” and accusing them of failing to usher in much-needed reforms.Speaking to hundreds of people in the eastern city of Benghazi, where the uprising began, de facto head of state Mohammed Megaryef paid homage to the "martyrs of the revolution” and the "true revolutionaries” who helped bring down Gaddafi.He insisted that Libya would not be allowed to become a "base for terrorism” and vowed to end the marginalisation of the east.On Friday, thousands of people gathered in the main cities of Tripoli and Benghazi to celebrate the initial February 15, 2011 protest that ignited the revolt two days later.The authorities have taken steps to prevent any violence on Sunday, when spontaneous celebrations were expected.Libya’s borders with Egypt and Tunisia have been closed since Thursday, for four days, and all international flights suspended except at the airports of Tripoli and Benghazi, while checkpoints have been set up around the two cities."We emphasise to our partners our determination that Libya does not become a base for or source of terrorism,” said Megaryef, who is president of the national assembly.There was no official programme for Sunday’s anniversary, but celebratory fireworks and revolutionary songs have filled the air across the country since Friday.Tahrir Square in Benghazi, where Megaryef was speaking, was set to be the focus of the celebration, with members of the government attending.Prime Minister Ali Zeidan has hailed the Libyan people’s rejection of "injustice and tyranny.”"The joy that motivated people in towns and villages on February 15 and 16 has allowed Libyans to prove to the world that they are a civilised people who revolted against injustice and tyranny to gain freedom,” Zeidan said.Opposition groups are demanding that former Gaddafi regime officials be barred from holding public office, and a leaflet circulated in Tripoli calls for a "popular revolt” and civil disobedience to bring down the current regime.It was unclear who was behind the leaflet and the calls to protest, but Libyan officials and several organisations, including Islamic groups, accuse remnants of the former regime of fomenting protests to "sow disorder and instability.”A number of opposition groups and civil society organisations, including those calling for federalism in eastern Libya, have temporarily suspend their calls to protest, initially planned for Friday, for fear of stoking violence."We understand the discontent of the population in certain regions, in particularly Benghazi,” which suffered from neglect under the Gaddafi regime, Megaryef said.