Egypt - Egypt's Muslim Brotherhood has warned of renewed turmoil if ousted leader Hosni Mubarak's ex-spy chief succeeds in a bid to become president.
Former vice-president and intelligence chief Omar Suleiman submitted his bid just before a deadline on Sunday.
The Muslim Brotherhood's candidate Khairat al-Shater described the move as an "insult" to the Egyptian people.
The presidential election, due to start on 23 May, will be the first since Mr Mubarak's overthrow in February 2011.
Twenty-three candidates have submitted bids to enter the race.
A provisional list of candidates will be published on Monday, but correspondents say the race looks set to be dominated by Islamists and officials who previously served in government.
The participation of 75-year-old Omar Suleiman promises to be particularly inflammatory, the BBC's Yolande Knell reports from Cairo.
Mobbed by supporters, he formally submitted his papers to the election commission half an hour before Sunday's deadline for nominations - having indicated on Friday his intention to run.
"I consider his entry an insult to the revolution and the Egyptian people," Khairat al-Shater, a millionaire businessman who was imprisoned during the rule of Mr Mubarak, told Reuters news agency.
"Omar Suleiman has made a big mistake. He will only win through forgery and, if this happens, the revolution will kick off again."
However, he played down fears of a clash between the Islamists and the military.
"Even if there are issues with the military council's handling of the transitional period, such issues must be resolved in a way that does not lead to a real clash with the armed forces," he said.
Mr Suleiman is not the only other Mubarak-era figure running for president. Former Prime Minister Ahmed Shafiq and former Foreign Minister Amr Moussa are also standing.
Meanwhile, the Muslim Brotherhood has registered a second candidate, Mohamed Mursi, who heads the movement's Freedom and Justice Party (FJP), after it emerged that Mr Shater might be unable to stand as he was only recently pardoned for a conviction.
The FJP dominated parliamentary elections earlier this year and now has almost half the seats in parliament.
Mr Shater is one of several hopefuls who have had their candidacy questioned, including the liberal candidate, Ayman Nour, and an Islamist preacher, Hazem Abu Ismail, who is known for his anti-American rhetoric.
Mr Abu Ismail is likely to be disqualified after reports that his mother held a US passport, contravening election laws.
Also on Sunday, Mr Shater announced that the Brotherhood would not support a $3.2bn emergency IMF loan requested by the government, unless the terms of the deal were changed.
The IMF has said it wants consensus among Egypt's main political groups before pressing forward with the loan.