30 January 2011 Last updated at 12:43 ET

Profile: Mohamed ElBaradei

Mohamed ElBaradei, a Nobel peace laureate and former head of the UN's nuclear watchdog, has emerged as a leading voice for political reform and likely challenger for Egypt's presidency since returning home in early 2010.

With thousands of demonstrators calling for President Hosni Mubarak to stand down, Mr ElBaradei has emerged as a leading figurehead of the opposition.

He is untested politically in Egypt and it is not clear what constituency he represents, but he may fit the bill as a consensus figure for a period of transition between the old regime and whatever follows it.

Mr ElBaradei joined the International Atomic Energy Agency (IAEA) in 1984 and worked his way up to director general 13 years later.

He secured a third term at the helm of the Vienna-based agency after the US eventually backed him, although ties between Washington and the IAEA have not been without tension over the years.

Mr ElBaradei agreed with the administration of US President George W Bush on a number of key nuclear-related issues, but was not afraid to speak his mind.

He particularly lambasted what he saw as double standards on the part of countries that have nuclear weapons, but which seek to prevent others from procuring them.

"We must abandon the unworkable notion that it is morally reprehensible for some countries to pursue weapons of mass destruction, yet morally acceptable for others to rely on them for security - and indeed to continue to refine their capacities and postulate plans for their use," he once declared.

Nuclear rows

Born in Egypt in 1942, Mr ElBaradei studied law at the University of Cairo. He began his career in the Egyptian Ministry of Foreign Affairs in 1964, and worked in Egypt's permanent mission to the UN both in New York and in Geneva.

He holds a doctorate in international law from New York University's law school.

In 1980 he became a senior fellow in charge of the International Law Programme at the UN's Institute for Training and Research.

Mr ElBaradei is married to Aida Elkachef, a teacher, with whom he has two children.

Daughter Laila is a lawyer who lives in London with her husband, an investment banker, and Mr ElBaradei's son, Mostafa, is an IT manager who lives in Cairo.

Mr ElBaradei's political credibility in the Middle East comes from the time when he questioned the claims about weapons of mass destruction that were being used to justify the US-led invasion of Iraq in 2003.

After taking over from Swedish diplomat Hans Blix in 1997, Mr ElBaradei employed diplomacy to deal with other nuclear rows in North Korea and Iran.

He insisted progress could be made even in the most difficult situations.

ElBaradei for President?

But his views on Iraq did not always accord with the Bush administration, and his approach to Iran was perceived as not tough enough by the US and its allies in the European Union.

Mr ElBaradei won the Nobel Peace Prize in 2005 for his efforts to prevent nuclear proliferation.

When he left the IAEA in November 2009, hundreds of his admirers defied warnings from Egyptian security forces three months later not to welcome him home at Cairo airport.

Mr ElBaradei is viewed as a credible potential challenger for presidential elections in 2011.

President Hosni Mubarak has ruled Egypt for nearly 30 years and there has been much speculation he is grooming his son Gamal to take over.

Analysts say that for some Egyptians Mr ElBaradei's appeal lies in the fact that he is a civilian - Egypt has been ruled by the military since the monarchy was overthrown more than 50 years ago - and that he is untainted by corruption allegations.

But pro-government newspapers have sought to portray him as out of touch with the reality of Egypt, and lacking in political experience.