Police use a ladder to evacuate people from a building near Lindt cafe
Police use a ladder to evacuate people from a building near Lindt cafe, where hostages are being held, in Martin Place in central Sydney December 15, 2014. Australian police locked down the centre of the country's biggest city on Monday after an armed assailant walked into the downtown Sydney cafe, took hostages and forced them to display an Islamic flag, igniting fears of a jihadist attack. Police said they knew of one armed assailant involved in the incident at the Lindt chocolate cafe in the heart of Sydney's financial district, but there could be more. REUTERS/David Gray

The Sydney siege in a café in iconic Martin Place was well-planned and organised to create "maximum publicity." A terrorism expert believes the armed man who has taken staff and customers hostages in the Lindt café wants to create "maximum impact" in sowing fear and terror among Australians.

Professor Jeff Lewis of the Royal Melbourne Institute of Technology believes the armed man, who has recently made his demands known through his hostages, has deliberately chosen Martin Place and the chocolate café opposite the offices of Seven Network to generate maximum publicity. Since the man is suspected of having ties with ISIS because of Black Standard flag hostages held up against the cafe's glass window, ISIS may have believed that Martin Place represents Western wealth and capitalism, according to a Daily Mail report.

Martin Place is considered as the most popular shopping destination in Sydney with upscale restaurants, bars and cafes, including high-end shops and designer stores. Lewis said ISIS may have selected a "soft target" which doesn't have maximum security to create heightened fear.

He said there is no confirmation as to who is actually behind the Sydney sieg, but he wouldn't say it was Jabhat al-Nusra, the Syrian-based extremist group with the same Black Standard flag that hostages were forced to hold. The professor explained that the Shahada flag is like a universal flag with the message "there is only one God." He said it was possible that ISIS supporters may be using the flag.

Previous reports in the past few months said ISIS has launched a global campaign to encourage supporters and followers to promote terror and just act. Lewis speculated that the Sydney siege may be part of some coordinated plan by the terrorist network.

The Grand Mufti of Australia has condemned the act of terror in Martin Place and called it a "criminal act," along with the other members of the Australian National Imams Council, CNN reported. The black flag hostages were forced to hold against the window has sparked fears that Sydney siege may be linked to ISIS. Australia has joined the U.S.-led coalition in the fight against ISIS in Iraq and Syria. The government has reportedly foiled a plot in September involving a public execution.