Mubarak, 81 and in power since 1981, has not said if he will run again in the 2011 election but, if not, most Egyptians believe he will seek to hand power to his politician son, Gamal, 46. Both deny this.

"The Egyptian doesn't believe his vote is credible," Egypt's former ambassador to Saudi Arabia, Abdallah Alashaal, 65, said.

"This regime wants to stay any way and by any means, so we have to circulate power," he told Reuters, adding that he was speaking to several parties but was seeking the backing of the Arab Socialist Party in particular.

Former UN nuclear watchdog chief Mohamed ElBaradei has already shaken up Egypt's calcified politics by saying he might seek the presidency but has set terms, including changes to the constitution's election rules, that will be tough to achieve.

The rules make it almost impossible for any candidate to run as an independent.

The alternative is to run for one of the opposition parties although they have very limited clout in a country ruled for decades by Mubarak's National Democratic Party. ElBaradei has said he would not seek any party's backing.

To enter an election for a party, the candidate must have held a senior party post for a year before the vote.

Mubarak swept the 2005 vote, Egypt's first multi-candidate race but marred by irregularities, according to democracy activists.

"The main motive to run for the elections is to test the political regime in Egypt," Alashaal told Reuters.

Alashaal, who now lectures at universities, echoed other opposition groups in calling for an end to emergency law that allows indefinite detentions.

Critics say the law, in place since 1981 following the assassination of President Anwar Sadat, is used to crackdown on dissent.

"Security should help in facilitating, not blocking, democracy," Alashaal said. Ayman Nour, who came a distant second to Mubarak in 2005, has also says he wants to run again.

He was jailed for forgery shortly after that vote, charges he says were political. That conviction is likely to prevent him running in 2011.-Reuters

The official Middle East News Agency said Mubarak, 81, underwent 'a successful operation on Saturday morning' to remove the gallbladder and was in intensive care where he was speaking with family members and his medical team.

'I can confirm that the operation went well,' said Annette Tuffs, spokeswoman for Heidelberg University Hospital.

Mubarak, who gave a news conference with German Chancellor Angela Merkel on Thursday, had also delegated power to the prime minister in 2004 when he had back surgery in Germany. He showed no signs of frailty at Thursday's news conference.

Mubarak has not said whether he will seek a sixth six-year term in the 2011 presidential election, nor has he designated a successor but many believe he will try to hand power to his politician son Gamal, 46, if he chooses not to stand again.

State media said Prime Minister Ahmed Nazif would assume the powers of the president 'until his return to undertake his duties,' adding that medical checks on Friday had shown chronic inflammation of Mubarak's gallbladder.

Gamal A.G. Soltan, director of the state-backed Al Ahram Center for Political and Strategic Studies, said the surgery was minor and the president had been active recently, pointing to trips around Egypt and meetings abroad.

'It seems there is no reason to be specially concerned at this point in time,' he said, adding talk about the succession was 'understandable considering the president's age.'

Egypt held its first multi-candidate election in 2005, a system not in place when Mubarak took over from Anwar Sadat who was gunned down by militants in 1981.

Mubarak easily won the 2005 vote which rights groups said was marred by abuses. Egyptian officials said it was fair.

Election rules make it almost impossible for anyone not backed by Mubarak's ruling party to stage a realistic run for the presidency, which analysts say means the next president is expected to come from the political or military establishment.

While many Egyptians believe Gamal Mubarak is most likely to succeed, it is far from certain, partly because he does not have a military background like Egypt's other presidents.

Omar Suleiman, Egypt's intelligence chief and a confidant of the president, has also been named a possible successor or king-maker. Analysts also say a dark-horse candidate from the military may emerge.

Mubarak underwent surgery for a slipped disc at a Munich hospital in 2004, an event that sparked rumors about the succession and sent jitters through Egypt's financial markets.

In 2003, he collapsed briefly during a speech to parliament. Officials said that was caused by a combination of cold medication and fasting during the Muslim holy month of Ramadan.-Reuters