Ex-UN nuclear watchdog chief and Nobel peace laureate Mohamed ElBaradei ended his candidacy for Egypt's presidency on Saturday, saying he could not run because there is still no real democracy there.

"My conscience does not allow me to run for the presidency or any other official position unless there is real democracy," ElBaradei said in a statement.

He said there was no room for him in Egyptian politics because old symbols of the regime were still running the country, and charged that preparations to draw a new constitution were 'botched'.

"I have examined the best ways of serving the goals of the revolution and I found that there is no official post for me, not even the presidency.

"Preparations are being made to elect a president before the establishment of a constitution that would organise relations among the (judicial, executive and legislative) powers and protect liberties," he said.

He praised the revolutionary youths who led massive popular uprisings that ousted president Hosni Mubarak last year, but said 'the former regime did not fall'.

"No decision was taken to purify state institutions, particularly state media and the judiciary, of symbols of the old regime," said ElBaradei.

He compared the revolution to a boat and charged that 'the captains of the vessel... are still treading old waters, as if the revolution did not take place'.

He said corruption was still rife in Egypt, which is being ruled by a military council since Mubarak was ousted in February following an 18-day popular uprising.

"We all feel that the former regime did not fall," he said.

Among the remaining 10 people who had declared their candidacy, the only one to enjoy international stature is former foreign minister and ex-Arab League chief Amr Mussa.

Mussa said he regrets ElBaradei's decision, official MENA news agency reported, but expressed confidence that he 'will pursue his efforts to rebuild the country'.

Asked by reporters in Beirut where he is attending a UN conference, Mussa confirmed: "Yes, I am a candidate in the presidential election."

ElBaradei denounced the 'repressive' policies of Egypt's new rulers, saying they were putting 'revolutionaries on trial in military court instead of protecting them and punishing those who killed their friends'.

His comments reflect growing disenchantment with the ruling Supreme Council of the Armed Forces (SCAF).

The SCAF has repeatedly pledged to cede full powers to civilian rule when a president is elected by the end of June, but there is widespread belief that the military wants to maintain a political role in the future.

The military has also come under fire over its human rights record and faced accusations that it has resorted to Mubarak-era tactics to stifle dissent.

Egypt witnessed deadly clashes between democracy protesters and regime forces in November - before parliamentary polls began - and again in December.

The SCAF has also kept in place several old regime figures such as Prosecutor General Abdel Meguid Mahmud and appointed a former Mubarak-era prime minister, Kamal al-Ganzuri, as the country's transitional premier.

Even its head, Field Marshal Hussein Tantawi, was long-time defence minister under Mubarak.

The former president is now on trial for the killing of hundreds of demonstrators in the revolt, and the prosecution has called for him to be hanged.

The liberal-minded ElBaradei was initially hailed as a hero upon his return to Egypt in February 2010 at the end of his tenure at the helm of the International Atomic Energy Agency.

Many Egyptians saw in him an ideal candidate to steer the most populous Arab country into democracy.

But rather than join a political party, the 69-year-old ElBaradei created a movement of his own to act as an umbrella for a range of opposition groups - the National Association for Change.

He boycotted elections in 2010, saying there was no hope of them being free and fair, and lost many supporters on the way.

His coalition, for which he did not even stand as a candidate, took a beating in the elections that wrapped up this week. Islamists won a crushing victory and are estimated to have clinched 70 per cent of seats in the next parliament.

In his statement ElBaradei said he will continue to 'work with the youth of Egypt' who unseated Mubarak in order to help them play an effective role in politics.

Once elections for an upper house are concluded in February, parliament is due to choose a 100-member panel to draft a new constitution. A new president is then to be elected by June under the timetable set by the military rulers.