By Edmund Blair and Marwa Awad

CAIRO, Nov 30 (Reuters) - Islamist President Mohamed Mursi is waging a high-stakes battle with Egypt's judges, many of them foes of his Muslim Brotherhood, which is bent on purging a judiciary seen as tainted by appointees of ousted leader Hosni Mubarak.

Judges called strikes and top courts halted work in protest at Mursi's decree last week that extended his powers and put his actions temporarily above legal challenge to try to speed up democratic transition in the Arab world's most populous nation.

The decree sparked eight days of confrontation and violence stoked by Egyptians accusing Mursi of taking over the role of "pharaoh" from Mubarak. More protests against Mursi's new, sweeping powers broke out on Friday.

Many judges say their independence is at risk - a risible notion for Islamists who believe many of their judicial critics sold out to Mubarak or sacrificed integrity for personal gain long ago, and are now throwing up obstacles to Mursi's rule.

"The bulk of the judiciary is good but there are those who are affiliates of the previous regime and the judiciary itself suffers from bribery and corruption," said Sobhi Saleh, a senior official in the Muslim Brotherhood's Freedom and Justice Party.

Mursi promises to preserve judicial independence in the new Egypt, but for decades he and his Brotherhood colleagues were at the sharp end of Mubarak's justice, jailed by exceptional courts under decades-old emergency laws on terrorism or other charges, or detained without trial for months or more.

These are recent memories for a group banned until a popular uprising ended Mubarak's 30-year rule in February 2011. But what really drew Brotherhood ire was a ruling in June that declared the Islamist-led parliament void, leading to its dissolution.

For them, it meant that even in the post-Mubarak era elected bodies could be threatened by an unreformed judicial system, which is split between liberal, secular-minded judges and those with Islamist leanings.

Even members of the judiciary admit that Mubarak and his army-backed predecessors whittled away at the system's integrity over decades and were able to buy off some officials.

But rights activists and others say Mursi's decree shows his idea of reform is to change personalities, not the institution, opening the way to interference in a new form.

"The judiciary is in danger from Mursi's wild adventures," said Abdel Nasser Abou al-Wafa, who was among 250 judges at a raucous meeting in Cairo where just 19 backed Mursi's moves. Others called for strike action by the courts.

"There are many judges who backed and benefited from Mubarak's regime but now there is fear the judiciary will be controlled by the Brotherhood," said judge Ahmed Hussein.

The upsurge in violence and the furore over Mursi's decree, which surprised even some of his close aides, are being watched by Washington worried at any instability in a nation that in 1979 became the first Arab state to make peace with Israel.

Mursi issued his decree just one day after winning praise from President Barack Obama for brokering a truce between Israel and Hamas Islamists in Gaza. Mursi has denied any link between his diplomatic success and his decision to announce his decree.

BATTLE OF WILL

The decree intensified debate about the religious and political direction the new Egypt is taking.

Mursi's lunge at the judiciary may bring him more headaches. After igniting nationwide protests against his decree, he has now rushed a new constitution towards a referendum, which judges - many of whom he has angered - are required to oversee.

"It's not very well thought through," said Heba Morayef of Human Rights Watch. "He has contributed to politicising this battle, so instead of talking about institutional reform on clear criteria, it is now a battle of political will."

In the decree, Mursi also empowered himself to sack the unpopular public prosecutor.

Mursi aides insist no judicial witch-hunt is planned, but Islamists clearly had public prosecutor Abdel Meguid Mahmoud in their sights, blaming him for failing to bring effective cases against Mubarak and his aides or those suspected of killing protesters in last year's uprising.

Mursi has now sacked Mahmoud for the second time, after his first attempt in October was blocked by the courts.

Many of Mursi's foes were just as angry with the prosecutor, but said his removal should have been left to the judiciary.

The president is now targeting the Supreme Constitutional Court, whose members were handpicked by Mubarak until his overthrow, when the judiciary took over that task.

"This is why some of the most notorious judges who were closely tied to the previous regime are lodged at the constitutional court," said Saleh of the FJP's legal committee.

The court's ruling in June to invalidate Egypt's lower house of parliament confirmed Islamist suspicions. Mursi shielded the upper house from legal challenge in his decree, fearing the court would mete out the same fate in a ruling due on Sunday.

TIT-FOR-TAT

Among the judges on the court, Egypt's highest, is Tahani al-Gebali, a Mubarak-era appointee who told Egypt's ON TV that Mursi had turned "himself into an illegitimate president" by breaching his oath, sworn before the constitutional court.

In comments to Reuters, Gebali dismissed accusations that the constitutional court was biased against any group.

In unusual tit-for-tat exchanges, the president indirectly criticised the court in a speech on Nov. 23. The court voiced "painful surprise" that Mursi had joined attacks on the panel.

Mursi praised the judiciary overall but vowed to "remove the cover" from corrupt elements trying to hide.

One of the president's most vocal adversaries is Ahmed al-Zend, head of the Judges Club - although his critics say he only found his enthusiasm for an independent judiciary after Mursi took office. Zend could not be reached for comment.

Mursi has sought dialogue with the judiciary to resolve the standoff over his decree. He held talks with a senior body of judges, the Supreme Judicial Council, agreeing that only decisions on "sovereign" matters would be immune from legal challenge. That was a compromise proposed by the council.

But the deal with the council does not mean universal backing in a judicial system where tensions exist between the secular-minded judges and those with Islamist inclinations.

Among the latter is Ahmed Mekky, Mursi's justice minister. A group named "Judges for the sake of Egypt" has backed Mursi's decree and pledged to oversee the constitutional referendum.

But there is a powerful strain opposed to Islamists.

"There are a few judges who are with the Muslim Brotherhood or Islamists but all the rest are moderate people," said Muhammad Said al-Ashmawy, 80, a retired judge who headed the Cairo state security court under Mubarak from 1983 to 1993 when Islamist militants were the main target of emergency rule.

Author of books critical of political Islam, Ashmawy said his round-the-clock personal protection was removed two months ago. "The Muslim Brotherhood doesn't want me to be guarded, not because of my judgements but because of my books," he said.