CAIRO - Egypt's President Abdel Fattah al-Sisi delivered a stern warning on Wednesday to anyone looking to challenge his rule, a day after opposition leaders called for a boycott of the March 26-28 presidential election."Be warned. What happened seven or eight years ago, will not happen again in Egypt," Sisi said, a reference to mass protests in 2011 that unseated long-term ruler Hosni Mubarak and ushered in years of political and economic turbulence."What didn't work then, will not work now. No ... it looks like you don't know me well," he said at the inauguration of the north African country's mammoth Zohr gas field.More than 150 politicians and activists called on Tuesday for voters to boycott the March election in which Sisi and a supporter-turned-challenger are the only contenders after a string of other candidates withdrew citing repression.Those calling for a boycott included lawyer Hamdeen Sabahy, who ran against Sisi in 2014's presidential election, and Hesham Genena, the former head of Egypt's anti-corruption watchdog who had been campaigning for ex-military chief of staff Sami Anan.Anan was arrested on Jan. 23 and halted his presidential bid after the army accused him of breaking the law by running for office without permission.Sisi said he could ask Egyptians to take to the streets and give him a "mandate" in the face of what he described as "villains". He did not specify who or what he meant."Listen, whoever wants to mess with Egypt and ruin it, has to do away with me first," said Sisi, who was elected in 2014, a year after he led the army to overthrow Islamist President Mohamed Mursi.