|ElBaradei told thousands of protesters in central Cairo that an uprising against Mubarak "cannot go back" [Reuters]
Mohamed ElBaradei, a Nobel peace laureate and the former head of the UN nuclear watchdog, has emerged as a key player in the Egyptian uprising against president Hosni Mubarak.
He has said he is prepared to lead a transitional government. Meanwhile, the National Coalition for Change, which groups several opposition movements including the Muslim Brotherhood, has tasked the veteran diplomat with negotiating with the Mubarak government.
Addressing a rally in Cairo's Tahrir square on the sixth day of protests, the 68-year-old told thousands of protesters that "we are on the right path, our strength is in our numbers".
"I ask you to be patient, change is coming ... Today as Egyptians, you have taken back your rights to life and freedom.
"What have begun cannot go back. As we said earlier, we have one main demand: the end of the regime and the beginning of a new stage."
Even before the mass protests began on January 25, ElBaradei was seen as a possible candidate in the presidential elections to be held later this year.
He left Egypt 28 years ago to work for the United Nations, but returned at least temporarily to Cairo in 2010 after resigning from the International Atomic Energy Association (IAEA).
He received an exuberant welcome from supporters who hoped he would stir up Egyptian politics by running for president. Days after retiring from the IAEA, ElBaradei had said that a decision on entering the presidential race would depend on guarantees of a fair election.
Untainted by the allegations of corruption that surround Mubarak's regime, ElBaradei is widely respected in Egypt.
He received the country's highest honour, the Nile Shas, in 2006.
However, some are sceptical of the former diplomat turned democracy advocate, saying he has been absent for Egypt for too long.
Ahead of the US invasion of Iraq in 2003, ElBaradei won public admiration around the world and angered Washington by challenging claims that Saddam Hussein was hiding a secret nuclear programme. He was proved right when no nuclear weapons were found.
He has earned a reputation for speaking his mind, and has criticised what he calls the double standards of countries that have nuclear weapons but prevent other countries from obtaining them.
ElBaradei was born on June 17, 1942, in Cairo, where his attorney father headed the bar association, a position that sometimes put him at odds with then president Gamal Abdel Nasser.
"My father taught me that you have to stand by your principles ... That you stand up for what you believe in"
Following in his father's footsteps, ElBaradei earned his law degree at the University of Cairo in 1962.
"My father taught me that you have to stand by your principles. He was president of the bar association and was preaching civil liberties and human rights during some of the most repressive years of the Nasser era.
"I think that's a lesson I remember from him...That you stand up for what you believe in," ElBaradei has said.
Two years after obtaining his law degree, ElBaradei joined the diplomatic service, and was assigned to the Egyptian missions to Geneva and New York, where he earned a doctorate in international law and later taught.
He has written that his New York years were among the most formative, helping him to broaden his world view.
Camp David negotiator
As special assistant to the Egyptian foreign minister, ElBaradei served on the negotiating team at the historic Camp David peace talks that led to Egypt's peace treaty and diplomatic relations with Israel.
He began his UN career in 1980, and was sent to Iraq in the wake of the 1991 Gulf war to dismantle Saddam's nuclear programme.
In 1997, he was chosen as head of the IAEA, a role that made him an international household name and led to confrontations with Washington, first over Iraq and later over Iran.
When Washington claimed that Iraq was buying uranium in Africa, ElBaradei dismissed the evidence before the UN Security Council as fake.
The Washington Post reported that ElBaradei's Vienna telephone was bugged by the US Central Intelligence Agency (CIA).
In 2005, ElBaradei and the IAEA were awarded the Nobel Peace Prize for their efforts "to prevent nuclear energy for being used for military purposes and to ensure that nuclear energy for peaceful purposes is used in the safest possible way."
ElBaradei stepped down as head of the IAEA late 2009, ending a 12-year term.
He is married to Aida Elkachef, a kindergarten teacher, and has two children, Laila and Mostafa.