* Sisi seen as saviour by supporters
* Reluctant to run for president
* Economic and political challenges (Adds quotes, details)
By Michael Georgy
CAIRO, March 4 (Reuters) - Egyptian armed forces chief Field Marshal Abdel Fattah al-Sisi has sent the clearest signal yet that he will run for president, saying he cannot ignore the demands of the "majority", the state news agency MENA reported on Tuesday.
Sisi, who ousted Egypt's first freely elected president, Mohamed Mursi of the Muslim Brotherhood, in July, said "official procedures" concerning his candidacy were expected in coming days.
Sisi, widely expected to win the presidency of the Arab world's most populous country, was speaking at a graduation ceremony at the Cairo war college.
MENA quoted him as saying he could "not turn his back on calls by the majority of Egyptians for him to run for president".
Most Egyptians regard him as a decisive figure who can end the political turmoil that has gripped Egypt since a popular uprising backed by the military toppled autocratic president Hosni Mubarak in 2011.
In his speech, Sisi said Egypt was witnessing difficult times that required the unity of the people, army and police, according to the state news agency MENA.
Sisi, who was Mubarak's military intelligence chief, has become so popular that his image appears on T-shirts and posters and even on chocolate bars.
Many liken Sisi to Gamal Abdel Nasser, the colonel who led a coup against the monarchy in 1952, set up an army-led autocracy and rounded up thousands of Muslim Brotherhood members.
Sisi deposed Mursi last July after millions of Egyptians protested in the streets against his rule, then unveiled a political roadmap said to lead to free and fair elections.
But since then, Egypt has witnessed the bloodiest political struggle in its modern history, with the Muslim Brotherhood trying to regain power through street protests and authorities mounting a relentless security crackdown against them.
Security forces killed hundreds in the streets, arrested thousands and authorities declared the Brotherhood a terrorist group, driving many of its estimated million followers underground.
The upheaval has scared away tourists vital for Egypt's struggling economy.
But oil powers Saudi Arabia, the United Arab Emirates and Kuwait, who were suspicious of the Brotherhood, came to Egypt's rescue, providing billions of dollars in aid.
Western diplomats who met with Sisi told Reuters he was reluctant to run for president, acutely aware of the enormous challenges of the job, and the reality that street protests helped remove two Egyptian leaders in three years.
While supporters regard Sisi as a saviour, opponents hold him responsible for what human rights groups say are widespread abuses, including torture of political detainees.
Aside from an ailing economy which grew by only one percent in the first quarter of this fiscal year, an energy crisis, industrial action and a tenacious Muslim Brotherhood, Sisi faces a fast-growing Islamist insurgency.
Militants based in the Sinai Peninsula have stepped up attacks on policemen and soldiers since Mursi's fall, killing hundreds. Attacks have spread to other parts of Cairo, with attacks occuring almost daily.
The most lethal group, Ansar Bayt al-Maqdis, said one of its suicide bombers tried to kill the interior minister last year and it claimed responsibility for killing two South Korean tourists last month.
(Writing by Michael Georgy; Editing by Angus MacSwan)