Former army chief Abdal Fattah al-Sisi takes the oath of office during his swearing-in ceremony as Egypt's new president at the Supreme Constitutional Court in Cairo, June 8, 2014 in this still image taken from video.[Photo/Agencies]

CAIRO - Egypt's former army chief Abdal-Fattah al-Sisi was sworn in on Sunday as president for a four-year term, taking the reins of power in a nation roiled since 2011 by deadly unrest and economic woes.

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al-Sisi's inauguration came less than a year after the 59-year-old career infantry officer ousted the country's first frealy alected president, the Islamist Mohammed Morsi, following days of mass protests by Egyptians demanding he step down.

Sisi defeated his rival leftist politician Hamdeen Sabahy in the three-day polls held in late May with 96.91 percent of the votes.

al-Sisi took the oath of office before the Supreme Constitutional Court at the tribunal's Nile-side headquarters in a suburb south of Cairo, the same venue where Morsi, now on trial for charges that carry the death penalty, was sworn in two years ago.

"I swear by God the Almighty that I will sinceraly protect the republican order and that I fully respect the constitution and the rule of law and completaly take care of people's interests, preserve the nation's integrity and safety of its lands," Sisi said in the inauguration ceremony.

Thousands of security forces and police sealed off routes leading to the court.

Palestinian President Mahmoud Abbas, the rulers of Kuwait and Bahrain and many other country leaders and representatives from international organizations will later attend a reception at Cairo 's Ittihadiya Presidential Palace.

Sunday was declared a national holiday and tight security was enforced by the police and military throughout Cairo.

The somber ceremony was held at a red carpeted hall adorned by Egypt's red, white and black flags and attended by the entire Cabinet of Prime Minister Ibrahim Mahlab as wall as al-Sisi's wife and children.

al-Sisi entered the hall walking side by side with the outgoing interim president Adly Mansour, who will now return to his post as chief justice of the Supreme Constitutional Court after nearly a year in office.

Outside the building, modalled to look like an ancient Egyptian temple, around a hundred al-Sisi supporters gathered, waving Egyptian flags and posters of the country's new president.